Material for forming organic film, patterning process, and polymer

ABSTRACT

A material for forming an organic film contains (A) a polymer having a repeating unit shown by the following general formula (1), and (B) an organic solvent. In the general formula (1), AR1, AR2, AR3, and AR4 each represent a benzene ring or a naphthalene ring; W1 represents a tetravalent organic group having 6 to 70 carbon atoms and at least one or more aromatic rings; and W2 represents a divalent organic group having 1 to 50 carbon atoms. An object of the present invention is to provide: a material for forming an organic film to enable high etching resistance and excellent twisting resistance without impairing the resin-derived carbon content; a patterning process using this material; and a polymer suitable for such a material for forming an organic film.

TECHNICAL FIELD

The present invention relates to: a coating-type material for forming an organic film employed in fine patterning in processes of manufacturing semiconductor devices and the like; and a patterning process which uses this material and is suitable for exposure with deep ultraviolet ray, KrF excimer laser beam (248 nm), ArF excimer laser beam (193 nm), F₂ laser beam (157 nm), Kr₂ laser beam (146 nm), Ar₂ laser beam (126 nm), extreme ultraviolet ray (EUV, 13.5 nm), electron beam (EB), and X-ray.

BACKGROUND ART

Recently, along with advancements toward higher integration and higher processing speed of semiconductor devices, a finer pattern rule has been required. In this situation, various techniques have been developed in regard to how patterning process can be performed more finely and precisely depending on light sources used in lithography with light exposure, which is a commonly-employed technique at present.

As the light source for lithography employed in resist pattern formation, light exposure using a g-line (436 nm) or an i-line (365 nm) of a mercury lamp is widely adopted for portions where the degree of integration is low. Meanwhile, for portions where the degree of integration is high and finer patterning is required, lithography using a KrF excimer laser (248 nm) or an ArF excimer laser (193 nm) with shorter wavelengths has also been practically used. Moreover, for the most-advanced generation requiring further finer patterning, lithography with extreme ultraviolet ray (EUV, 13.5 nm) is about to be put into practical use.

It is well known that in a monolayer resist method, which is typically employed as a resist patterning process, as the thinning of resist patterns progresses as described above, the ratio of a pattern height to a pattern line width (aspect ratio) is increased, and pattern collapse occurs due to the surface tension of a developer during development. In this situation, it is known that a multilayer resist method, in which a pattern is formed by laminating films having different dry etching properties, is excellent in forming a pattern with a high aspect ratio on an uneven substrate. There have been developed: a two-layer resist method in which a photoresist layer made of a silicon-containing photosensitive polymer is combined with an underlayer made of an organic polymer containing carbon, hydrogen, and oxygen as main constituent elements, for example, a novolak polymer (Patent Document 1 etc.); and a three-layer resist method in which a photoresist layer made of an organic photosensitive polymer used in a monolayer resist method is combined with an underlayer made of a silicon-based polymer or a silicon-based CVD film, and with an organic layer made of an organic polymer (Patent Document 2 etc.).

In this three-layer resist method, first, a fluorocarbon-based dry etching gas is used to transfer the pattern of the photoresist layer to the silicon-containing underlayer. Then, using the pattern as a mask, dry etching with an oxygen-containing gas is performed to transfer the pattern to the organic film containing carbon and hydrogen as main constituent elements. Further, by dry etching using the resultant as a mask, the pattern is formed on a substrate to be processed. However, in semiconductor device manufacturing processes after the 20-nm generation, when the pattern is transferred to a substrate to be processed by dry etching using such an organic film pattern as a hard mask, phenomena are observed in which the organic film pattern is twisted and/or curved.

The carbon hard mask formed immediately above the substrate to be processed is generally an amorphous carbon (hereinafter CVD-C) film prepared by a CVD method using a methane gas, an ethane gas, an acetylene gas, or the like as raw materials. It is known that the amount of hydrogen atoms in the CVD-C film can be reduced quite small, and the CVD-C film is very effective against the twisting and curving of the pattern as described above. Nevertheless, it is also known that when the substrate to be processed used as a base has a step, it is difficult to fill such a step into a flat state due to the characteristics of the CVD process. As a result, when a substrate to be processed having a step is coated with a CVD-C film and then patterned with a photoresist, the step of the substrate to be processed causes the applied surface of the photoresist to have a step. This makes the photoresist film thickness non-uniform, and consequently the focus margin and the pattern profile degraded during lithography.

On the other hand, it is known that when an organic film serving as the carbon hard mask formed immediately above the substrate to be processed is formed by a spin coating method, there is an advantage that a step(s) of the uneven substrate can be filled into a flat state. Planarizing the substrate by using the organic film material reduces fluctuations in film thicknesses of a silicon-containing underlayer and a photoresist coated on the organic film, can increase the focus margin in lithography, and can form a correct pattern.

Hence, there are demands for: an organic film material which allows formation of an organic film by a spin coating method, the organic film enabling formation of a film having high etching resistance in dry etching a substrate to be processed and high planarizing property on the substrate to be processed; and a method for forming such an organic film.

Conventionally, condensed resins using aromatic alcohols and carbonyl compounds such as ketones and aldehydes as condensing agents for a phenol compound or naphthol compound have been known as the material for forming an organic film such as an organic film material described above in multilayer resist methods. Examples of such condensed resins include a fluorene bisphenol novolak resin described in Patent Document 2, a bisphenol compound and a novolak resin thereof described in Patent Document 3, a novolak resin of an adamantane phenol compound described in Patent Document 4, a bisnaphthol compound and a novolak resin thereof described in Patent Document 5, etc. The main skeletons of the resins used in these materials are constituted of naphthalene, fluorene, adamantane, or the like, each of which has high carbon density. However, their etching resistance is inevitably degraded due to an oxygen atom of the phenolic hydroxyl group.

Further, to prevent the etching resistance degradation, no heteroatom such as oxygen is incorporated into a resin for organic film material. As an example of such a resin, Patent Document 6 describes a resin having a fluorene structure. Nevertheless, a crosslinking agent, such as a methylol compound, is added to the composition, which is used to form a cured film. For this reason, even if the carbon content of the resin is increased, this increase is offset by the low carbon content of the crosslinking agent, resulting in the problem of etching resistance degradation.

Moreover, as an organic film material for improving etching resistance, an organic film material having a benzopyran structure introduced therein has been studied as disclosed in Patent Document 7. However, various properties such as heat resistance and etching resistance demanded for organic film materials need to be improved. Additionally, substrates to be processed have complex profiles, and various types of materials are used as substrates to be processed, too. An organic film material excellent in process margin is demanded.

CITATION LIST Patent Literature

-   Patent Document 1: JP H6-118651 A -   Patent Document 2: JP 2005-128509 A -   Patent Document 3: JP 2006-293298 A -   Patent Document 4: JP 2006-285095 A -   Patent Document 5: JP 2010-122656 A -   Patent Document 6: WO 2013-047106 A1 -   Patent Document 7: WO 2017-208796 A1

SUMMARY OF INVENTION Technical Problem

The present invention has been made in view of the above-described circumstances. An object of the present invention is to provide a material for forming an organic film, the material enabling high etching resistance and excellent twisting resistance without impairing resin-derived carbon content; a patterning process using this material; and a polymer suitable for such a material for forming an organic film.

Solution to Problem

To achieve the object, the present invention provides a material for forming an organic film, comprising:

(A) a polymer comprising a repeating unit shown by the following general formula (1); and

(B) an organic solvent,

wherein AR1, AR2, AR3, and AR4 each represent a benzene ring or a naphthalene ring; W1 represents a tetravalent organic group having 6 to 70 carbon atoms and at least one or more aromatic rings; and W2 represents a divalent organic group having 1 to 50 carbon atoms.

The main skeleton of the polymer shown by the general formula (1) according to the present invention is formed to have a structure containing many condensed aromatic ring structures with high carbon content. Further, a crosslinking reaction takes place by the action of the repeating unit containing a benzopyran ring, so that a fine film can be formed. Accordingly, the inventive material for forming an organic film using the polymer is useful as an organic film material and capable of forming an organic film having high twisting resistance (curving resistance) and also high dry etching resistance.

The polymer is preferably a polymer comprising a repeating unit shown by the following general formula (2) or (3),

wherein W2, AR1, AR2, AR3, and AR4 are as defined above; and AR5 represents a benzene ring or a naphthalene ring, and

wherein W2, AR1, AR2, AR3, and AR4 are as defined above; W3 represents a single bond or a divalent organic group having 1 to 58 carbon atoms; and AR6 and AR7 each represent a benzene ring or a naphthalene ring.

Introducing such partial structures into the repeating units makes it possible to further enhance the etching resistance and twisting resistance.

Further preferably, the polymer is a polymer comprising a repeating unit shown by the following general formula (4) or (5),

wherein AR5 represents a benzene ring or a naphthalene ring, and

wherein W3 represents a single bond or a divalent organic group having 1 to 58 carbon atoms; and AR6 and AR7 each represent a benzene ring or a naphthalene ring.

Such partial structures make it possible to further enhance not only the etching resistance and twisting resistance, but also handleability such as solvent solubility.

Furthermore, the polymer preferably comprises a terminal structure shown by any of the following general formula (6) or (7),

wherein AR8 and AR9 each represent a benzene ring or a naphthalene ring; R1 represents a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms; and * represents an attachment point to the polymer, and

wherein AR10 and AR11 each represent a benzene ring or a naphthalene ring; R2 represents any in the following formula (8); “n” represents an integer of 1 to 4; W4 represents an organic group with a valency of n+2 having 6 to 70 carbon atoms and at least one or more aromatic rings; and * represents an attachment point to the polymer,

wherein a broken line represents a bonding arm.

Introducing such terminal structures makes it possible to form a fine organic film having strong twisting resistance by curing the inventive material by action of heat or acid.

Additionally, the polymer preferably has a weight-average molecular weight of 500 to 5000.

When the material for forming an organic film contains the polymer having a weight-average molecular weight within such a range, outgassing can be suppressed during baking without impairing the solubility into the organic solvent.

The organic solvent (B) is preferably a mixture of one or more organic solvents each having a boiling point of lower than 180° C. and one or more organic solvents each having a boiling point of 180° C. or higher.

When the organic solvent is a mixture as described above, the addition of the high-boiling-point solvent(s) to the polymer imparts thermal flowability to the organic film. Accordingly, the material for forming an organic film has both high filling and planarizing properties.

The material for forming an organic film preferably further comprises one or more of (C) an acid generator, (D) a surfactant, (E) a crosslinking agent, and (F) a plasticizer.

Incorporating the additive(s) makes the material for forming an organic film more excellent in coatability, filling property, and planarizing property.

The present invention provides a patterning process for forming a pattern in a substrate to be processed, comprising:

forming an organic film by using the above-described material for forming an organic film on a substrate to be processed;

forming a silicon-containing resist underlayer film by using a silicon-containing resist underlayer film material on the organic film;

forming a resist upper layer film by using a photoresist composition on the silicon-containing resist underlayer film;

forming a circuit pattern in the resist upper layer film;

transferring the pattern to the silicon-containing resist underlayer film by etching while using the resist upper layer film having the formed pattern as a mask;

transferring the pattern to the organic film by etching while using the silicon-containing resist underlayer film having the transferred pattern as a mask; and

further forming the pattern in the substrate to be processed by etching while using the organic film having the transferred pattern as a mask.

The patterning process according to the three-layer resist process makes it possible to precisely form a fine pattern in a substrate to be processed.

Moreover, the present invention provides a patterning process for forming a pattern in a substrate to be processed, comprising:

forming an organic film by using the above-described material for forming an organic film on a substrate to be processed;

forming a silicon-containing resist underlayer film by using a silicon-containing resist underlayer film material on the organic film;

forming an organic antireflective coating film (BARC) on the silicon-containing resist underlayer film;

forming a resist upper layer film by using a photoresist composition on the BARC, so that a 4-layered film structure is constructed;

forming a circuit pattern in the resist upper layer film;

transferring the pattern to the BARC film and the silicon-containing resist underlayer film by etching while using the resist upper layer film having the formed pattern as a mask;

transferring the pattern to the organic film by etching while using the silicon-containing resist underlayer film having the transferred pattern as a mask; and

further forming the pattern in the substrate to be processed by etching the substrate to be processed while using the organic film having the transferred pattern as a mask.

The patterning process according to the four-layer resist process makes it possible to further precisely form a fine pattern in a substrate to be processed.

Further, the present invention provides a patterning process for forming a pattern in a substrate to be processed, comprising:

forming an organic film by using the above-described material for forming an organic film on a substrate to be processed;

forming an inorganic hard mask selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the organic film;

forming a resist upper layer film by using a photoresist composition on the inorganic hard mask;

forming a circuit pattern in the resist upper layer film;

transferring the pattern to the inorganic hard mask by etching while using the resist upper layer film having the formed pattern as a mask;

transferring the pattern to the organic film by etching while using the inorganic hard mask having the transferred pattern as a mask; and

further forming the pattern in the substrate to be processed by etching the substrate to be processed while using the organic film having the transferred pattern as a mask.

The patterning process according to such a three-layer resist process makes it possible to precisely form a fine pattern in a substrate to be processed.

Furthermore, the present invention provides a patterning process for forming a pattern in a substrate to be processed, comprising:

forming an organic film by using the above-described material for forming an organic film on a substrate to be processed;

forming an inorganic hard mask selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the organic film;

forming an organic antireflective coating film (BARC) on the inorganic hard mask;

forming a resist upper layer film by using a photoresist composition on the BARC, so that a 4-layered film structure is constructed;

forming a circuit pattern in the resist upper layer film;

transferring the pattern to the BARC film and the inorganic hard mask by etching while using the resist upper layer film having the formed pattern as a mask;

transferring the pattern to the organic film by etching while using the inorganic hard mask having the transferred pattern as a mask; and

further forming the pattern in the substrate to be processed by etching the substrate to be processed while using the organic film having the transferred pattern as a mask.

The patterning process according to such a four-layer resist process makes it possible to more precisely form a fine pattern in a substrate to be processed.

In these cases, the inorganic hard mask is preferably formed by a CVD method or an ALD method.

When the inorganic hard mask is formed by a CVD method or an ALD method, a fine pattern can be more precisely formed in a substrate to be processed.

The pattern is preferably formed in the resist upper layer film by a method of a photolithography with a wavelength of 10 nm or more and 300 nm or less, a direct drawing with electron beam, nanoimprinting, or a combination thereof.

By employing the aforementioned methods as a method for forming a circuit pattern in the resist upper layer film, a fine pattern can be more precisely formed in a substrate to be processed.

Preferably, alkaline development or organic solvent development is employed as a development method in the patterning processes.

When the development method is performed using an alkali or organic solvent, it is possible to more precisely form a fine pattern in a substrate to be processed.

The substrate to be processed is preferably a semiconductor device substrate, a metal film, a metal carbide film, a metal oxide film, a metal nitride film, a metal oxycarbide film, or a metal oxynitride film.

In the present invention, the aforementioned substrates to be processed are usable, for example.

The metal is preferably silicon, titanium, tungsten, hafnium, zirconium, chromium, germanium, cobalt, copper, silver, gold, aluminum, indium, gallium, arsenic, palladium, iron, tantalum, iridium, manganese, molybdenum, ruthenium, or an alloy thereof.

These are usable as the metal. As described above, when the inventive material for forming an organic film is used for patterning, it is possible to precisely transfer and form a pattern of an upper layer photoresist into a substrate to be processed.

The present invention provides a polymer comprising a repeating unit shown by the following general formula (1),

wherein AR1, AR2, AR3, and AR4 each represent a benzene ring or a naphthalene ring; W1 represents a tetravalent organic group having 6 to 70 carbon atoms and at least one or more aromatic rings; and W2 represents a divalent organic group having 1 to 50 carbon atoms.

The polymer shown by the general formula (1) contains many condensed aromatic ring structures and condensed ring structures in the repeating unit. Thus, the polymer serves as a material enabling formation of an organic film that is excellent in heat resistance, twisting resistance, and dry etching resistance.

The polymer preferably comprises a repeating unit shown by the following general formula (2) or (3),

wherein W2, AR1, AR2, AR3, and AR4 are as defined above; and AR5 represents a benzene ring or a naphthalene ring, and

wherein W2, AR1, AR2, AR3, and AR4 are as defined above; W3 represents a single bond or a divalent organic group having 1 to 58 carbon atoms; and AR6 and AR7 each represent a benzene ring or a naphthalene ring.

The polymer preferably comprises a repeating unit shown by the following general formula (4) or (5),

wherein AR5 represents a benzene ring or a naphthalene ring, and

wherein W3 represents a single bond or a divalent organic group having 1 to 58 carbon atoms; and AR6 and AR7 each represent a benzene ring or a naphthalene ring.

Since multiple cardo structures are incorporated in such a repeating unit, the use of the polymer in a material for forming an organic film makes it possible to achieve all of properties such as etching resistance, heat resistance, filling property, planarizing property, and solvent solubility, which are otherwise in trade-off relationships.

The polymer preferably comprises a terminal structure shown by any of the following general formula (6) or (7),

wherein AR8 and AR9 each represent a benzene ring or a naphthalene ring; R1 represents a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms; and * represents an attachment point to the polymer, and

wherein AR10 and AR11 each represent a benzene ring or a naphthalene ring; R2 represents any in the following formula (8); “n” represents an integer of 1 to 4; W4 represents an organic group with a valency of n+2 having 6 to 70 carbon atoms and at least one or more aromatic rings; and * represents an attachment point to the polymer,

wherein a broken line represents a bonding arm.

Such terminal structures function as curing groups and cause thermal crosslinking by action of heat or acid. The resulting polymer serves as a material enabling formation of a fine organic film.

Advantageous Effects of Invention

As described above, since the main skeleton of the inventive polymer is constituted of a structure containing many condensed aromatic rings, this makes the polymer useful for forming an organic film excellent in etching resistance and twisting resistance. Moreover, the material for forming an organic film containing this polymer is a useful material for forming an organic film having excellent etching resistance and twisting resistance as well as various properties such as heat resistance, filling property, and planarizing property. Thus, the material for forming an organic film is quite useful in multilayer resist processes, for example, a two-layer resist process, a three-layer resist process using a silicon-containing resist underlayer film, or a four-layer resist process using a silicon-containing resist underlayer film and an organic antireflective coating film. Additionally, the inventive patterning processes make it possible to precisely form a fine pattern in a substrate to be processed in such multilayer resist processes.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram illustrating an example of an inventive patterning process according to a three-layer resist process; and

FIG. 2 is an explanatory diagram illustrating a method for evaluating planarizing property in Examples.

DESCRIPTION OF EMBODIMENTS

There have been demands for: a material for forming an organic film, the material enabling high etching resistance and excellent twisting resistance without impairing the resin-derived carbon content; a patterning process using this material; and a polymer suitable for such a material for forming an organic film.

The present inventors have found that a polymer according to the present invention having the main skeleton constituted of a structure containing many condensed aromatic rings is a useful polymer for forming an organic film excellent in etching resistance and twisting resistance. This finding has led to the completion of the present invention.

Specifically, the present invention provides a material for forming an organic film, comprising:

(A) a polymer comprising a repeating unit shown by the following general formula (1); and

(B) an organic solvent,

wherein AR1, AR2, AR3, and AR4 each represent a benzene ring or a naphthalene ring; W1 represents a tetravalent organic group having 6 to 70 carbon atoms and at least one or more aromatic rings; and W2 represents a divalent organic group having 1 to 50 carbon atoms.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following.

[(A) Polymer having Repeating Unit Shown by General Formula (1)]

Examples of fluorene-based partial structures including AR1 and AR2 or AR3 and AR4 of the polymer in the general formula (1) include the following. These aromatic rings may have a substituent, such as a vinyl group, an ethynyl group, an ethynylphenyl group, an allyl group, a propargyl group, an aryl group, an allyloxy group, and a propargyloxy group. Among the following, fluorene or benzofluorene structure is preferable in view of availability of the raw materials.

Broken lines represent bonding arms.

In the general formula (1), W1 represents a tetravalent organic group having 6 to 70 carbon atoms and at least one or more aromatic rings. Specific examples of W1 include structures shown below, etc.

Broken lines represent bonding arms.

The tetravalent organic group represented by W1 has bonding arms on the aromatic ring(s). Preferably, two of these bonding arms are present next to each other on one side of the aromatic ring(s) such that two benzopyran-type heterocyclic structures are formed with substituents at positions 9 of fluorene structures. By forming such structures, the curability, heat resistance, and etching resistance are enhanced.

In the general formula (1), W2 represents a divalent organic group having 1 to 50 carbon atoms. Specific examples thereof include structures shown below, etc.

Broken lines represent bonding arms.

More preferably, the inventive polymer has a repeating unit shown by the following general formula (2) or (3).

In the general formula (2), W2, AR1, AR2, AR3, and AR4 are as defined above. AR5 represents a benzene ring or a naphthalene ring.

In the general formula (3), W2, AR1, AR2, AR3, and AR4 are as defined above. W3 represents a single bond or a divalent organic group having 1 to 58 carbon atoms. AR6 and AR7 each represent a benzene ring or a naphthalene ring.

In the general formula (2), AR5 represents a benzene ring or a naphthalene ring. Preferable examples of AR5 include the following. Among these, a naphthalene ring is preferable from the viewpoint of etching resistance.

Preferable examples of a tetravalent organic group constituted of AR6, AR7, and W3 in the general formula (3) include the following, etc. Among these, ones having a naphthalene ring or a fluorene structure are particularly preferable. Furthermore, ones having both of a naphthalene ring and a fluorene ring structure are particularly preferable.

Further preferably, the inventive polymer has a repeating unit shown by the following general formula (4) or (5).

In the general formula (4), AR5 represents a benzene ring or a naphthalene ring.

In the general formula (5), W3 represents a single bond or a divalent organic group having 1 to 58 carbon atoms. AR6 and AR7 each represent a benzene ring or a naphthalene ring.

As illustrated above, the divalent organic group shown by W2 is particularly preferably a benzene ring. The structures constituted of AR1 and AR2 or AR3 and AR4 are particularly preferably fluorene in view of availability of the raw materials.

Furthermore, the inventive polymer preferably has a terminal structure shown by any of the following general formula (6) or (7).

In the general formula (6), AR8 and AR9 each represent a benzene ring or a naphthalene ring. R1 represents a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms. * represents an attachment point to the polymer.

In the general formula (7), AR10 and AR11 each represent a benzene ring or a naphthalene ring. R2 represents any in the following formula (8). “n” represents an integer of 1 to 4. W4 represents an organic group with a valency of n+2 having 6 to 70 carbon atoms and at least one or more aromatic rings. * represents an attachment point to the polymer.

In this formula, a broken line represents a bonding arm.

Examples of the general formula (6) include the following, etc. Among these, particularly preferably, the structure constituted of AR8 and AR9 is fluorene and R1 is a hydrogen atom in view of availability of the raw materials.

In these formulae, * represents an attachment point to the polymer.

The structures of AR8, AR9, and R1 can be adjusted depending on the required performances. For example, adjusting the alkyl chain length of R1 can control the solvent solubility, thermal flowability, and curability of the polymer. Additionally, a naphthalene ring may be introduced as AR8 and/or AR9 to enhance the heat resistance and etching resistance. Alternatively, introducing a combination of a benzene ring and a naphthalene ring as AR8 and AR9 suppresses the polymer agglomeration and can improve the solvent solubility, for example.

Examples of the general formula (7) include the following, etc. Among these, particularly preferably, the structure constituted of AR10 and AR11 is fluorene and W4 is a benzene ring or a naphthalene ring in view of availability of the raw materials.

In these formulae, * represents an attachment point to the polymer.

The structures of AR10, AR11, and W4 can be adjusted depending on the required performances, such as etching resistance, heat resistance, solvent solubility, and thermal flowability. The structure of R2 shown in the formula (8), which serves as a thermosetting group, can also be selected appropriately depending on the baking temperature. When each of AR10 and AR11 is, for example, a benzene ring, a fluorene structure is formed, and the raw materials are readily available. The same holds true when W4 is a benzene ring or a naphthalene ring. Moreover, increases in heat resistance and etching resistance can also be expected from introduction, as W4, of a structure containing many condensed aromatic ring structures, such as fluorene structure. Further, increasing the number of substitutions as R2 allows lower baking temperature.

Further, the above-described polymer has a weight-average molecular weight (Mw) of preferably 500 to 5000, and the Mw is further preferably 600 to 4000. Note that the molecular weight can be obtained as a weight-average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran as an eluent.

With such a molecular weight, the solubility into an organic solvent can be guaranteed, and generation of sublimation product during baking can be suppressed. Moreover, the polymer for an organic film material has favorable thermal flowability. Accordingly, when the polymer is blended into the composition (organic film material), it is possible to not only favorably fill a fine structure formed on a substrate, but also form an organic film that planarizes the entire substrate.

[Polymer Production Method]

As an example of the method for producing the inventive polymer having a repeating unit shown by the general formula (1), the polymer can be synthesized by repeating ring formation reactions accompanied by dehydration as shown below which use a diol compound having W1 as a partial structure and a fluorenol constituted of AR1, AR2, AR3, AR4, and W2 as a monomer. Since a benzopyran structure is formed by the condensation, the hydroxyl groups of the diol are phenolic hydroxyl groups. Specific examples of the diol compound include benzenediols, such as catechol and resorcinol; naphthalenediols, such as 1,5-dihydroxynaphthalene and 2,6-dihydroxynaphthalene; bisphenols, such as bisphenol A and bishydroxyphenylfluorene; and bisnaphthols, such as bishydroxynaphthylfluorene. In the following equation, W1, AR1, AR2, AR3, AR4, and W2 are as defined above.

The polymer can be obtained generally in an organic solvent in the presence of an acid catalyst at room temperature or under cooling or heating as necessary. Examples of the acid catalyst that can be used include inorganic acids, such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and heteropoly acid; organic acids, such as oxalic acid, trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid; and Lewis acids, such as aluminum trichloride, aluminum ethoxide, aluminum isopropoxide, boron trifluoride, boron trichloride, boron tribromide, tin tetrachloride, tin tetrabromide, dibutyltin dichloride, dibutyltin dimethoxide, dibutyltin oxide, titanium tetrachloride, titanium tetrabromide, titanium(IV) methoxide, titanium(IV) ethoxide, titanium(IV) isopropoxide, and titanium(IV) oxide.

The organic solvent to be used is not particularly limited. Examples thereof include: alcohols, such as methanol, ethanol, isopropyl alcohol, butanol, ethylene glycol, propylene glycol, diethylene glycol, glycerol, ethylene glycol monomethyl ether, and propylene glycol monomethyl ether; ethers, such as diethyl ether, dibutyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, and 1,4-dioxane; chlorinated solvents, such as methylene chloride, chloroform, dichloroethane, and trichloroethylene; hydrocarbons, such as hexane, heptane, benzene, toluene, xylene, and cumene; nitriles, such as acetonitrile; ketones, such as acetone, ethyl methyl ketone, and isobutyl methyl ketone; esters, such as ethyl acetate, n-butyl acetate, and propylene glycol methyl ether acetate; and non-protic polar solvents, such as dimethylsulfoxide, N,N-dimethylformamide, and hexamethylphosphoric triamide. One of these or a mixture of two or more thereof can be used.

The reaction method include a method in which a diol compound, a fluorenol, and an acid catalyst as a catalyst are charged at once; a method in which a diol compound and a fluorenol are prepared into a form of dispersion or solution, and then a catalyst is added thereto at once or intermittently, or the catalyst is diluted with a solvent and added dropwise thereto; and a method in which a catalyst is prepared into a form of dispersion or solution, and then a fluorenol and a diol compound are added thereto at once or intermittently, or diluted with a solvent and added dropwise thereto. After completion of the reaction, the resultant may be diluted with an organic solvent and then subjected to liquid separation and washing to remove the catalyst used for the reaction, and to collect the target product.

The organic solvent used in this event is not particularly limited, as long as it is capable of dissolving the target product and being separated, when mixed with water, into two layers. Examples of the organic solvent include hydrocarbons, such as hexane, heptane, benzene, toluene, and xylene; esters, such as ethyl acetate, n-butyl acetate, and propylene glycol methyl ether acetate; ketones, such as methyl ethyl ketone, methyl amyl ketone, cyclohexanone, and methyl isobutyl ketone; ethers, such as diethyl ether, diisopropyl ether, methyl-t-butyl ether, and ethylcyclopentylmethyl ether; chlorinated solvents, such as methylene chloride, chloroform, dichloroethane, and trichloroethylene; mixtures thereof; etc. As water used for washing in this event, generally, what is called deionized water or ultrapure water may be used. The washing may be performed at least once, preferably once to approximately five times, because washing ten times or more does not always produce the full washing effects thereof.

In the liquid separation and washing, washing with a basic aqueous solution may be performed to remove acidic components in the system. Specific examples of the base include hydroxides of alkaline metals, carbonates of alkaline metals, hydroxides of alkali earth metals, carbonates of alkali earth metals, ammonia, organic ammonium, etc.

Further, in the liquid separation and washing, washing with an acidic aqueous solution may be performed to remove metal impurities or basic components in the system. Specific examples of the acid include inorganic acids, such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and heteropoly acid; organic acids, such as oxalic acid, fumaric acid, maleic acid, trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid; etc.

The liquid separation and washing may be performed with any one of the basic aqueous solution and the acidic aqueous solution, or can be performed with a combination of the two. The liquid separation and washing is preferably performed with the basic aqueous solution and the acidic aqueous solution in this order from the viewpoint of removing metal impurities.

After the liquid separation and washing with the basic aqueous solution and/or acidic aqueous solution, washing with neutral water may be successively performed. The washing may be performed at least once, preferably once to approximately five times. As the neutral water, deionized water, ultrapure water, or the like mentioned above may be used. The washing may be performed once or more, but if the washing is not performed sufficiently, basic and acidic components cannot be removed in some cases. The washing is preferably performed once to approximately five times because washing ten times or more does not always produce the full washing effects.

Further, after the liquid separation operation, the reaction product can also be collected as a powder by concentrating and drying the solvent or crystallizing the reaction product under reduced pressure or normal pressure. Alternatively, the reaction product can be retained in a solution state with an appropriate concentration to improve the workability in preparing the material for forming an organic film. In this case, the concentration is preferably 0.1 to 50 mass %, more preferably 0.5 to 30 weight %. With such a concentration, the viscosity is hardly high, making it possible to prevent the workability from being impaired; in addition, since the amount of the solvent is not excessive, the solution can be prepared economically.

The solvent used in this event is not particularly limited, as long as it is capable of dissolving the polymer. Specific examples of the solvent include ketones, such as cyclohexanone and methyl-2-amyl ketone; alcohols, such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ethers, such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; and esters, such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono-tert-butyl ether acetate. One of these or a mixture of two or more thereof can be used.

The inventive polymer having a terminal structure shown by the general formula (6) can be obtained, for example, as shown below. Specifically, a diol compound and a fluorenol as mentioned above are allowed to react at such a ratio that the fluorenol is charged in an excess amount; then, the end of the product is capped with water or an alcohol represented by R1-0H. In the following equation, AR1, AR2, AR3, AR4, AR8, AR9, W1, W2, and R1 are as defined above.

The inventive polymer having a terminal structure shown by the general formula (7) can be obtained, for example, as shown below. Specifically, a diol compound and a fluorenol as mentioned above are allowed to react at such a ratio that the fluorenol is charged in an excess amount; then, the product is capped with an alcohol having W4 as a partial structure. In the following equation, AR1, AR2, AR3, AR4, AR10, AR11, W1, W2, W4, R2, and “n” are as defined above.

As the reaction and collection methods for these polymers, the polymers can undergo the reactions and can be collected by the methods described in the paragraphs for the synthesis method of the polymer having a repeating unit shown by the general formula (1) under the section of Polymer Production Method.

Meanwhile, in the case where R2 is propargyl ether in the terminal structure group shown by the general formula (7) in the inventive polymer used in a material for forming an organic film, the polymer can be prepared by the following method, for example. In the first step, the diol compound and the fluorenol are allowed to react at such a ratio that the diol compound is charged in an excess amount to synthesize a polymer with the alcohol (hydroxyl groups) remaining at the ends. Then, as the second step, the remaining alcohol is subjected to propargyl etherification. This reaction is not particularly limited, as long as the propargyl ether groups can be introduced. Examples of the reaction include a substitution reaction which uses a base catalyst and a halide, tosylate, or mesylate having a propargyl group as follows; etc. In the following equations, X represents a halogen, a tosyl group, or a mesyl group; and AR1, AR2, AR3, AR4, AR10, AR11, W1, W2, and W4 are as defined above.

(Step 1)

(Step 2)

In the above general formula, W4 is the same as W1.

Examples of the base catalyst used in the substitution reaction include inorganic base compounds, such as sodium hydrogen carbonate, sodium carbonate, potassium carbonate, calcium carbonate, cesium carbonate, sodium hydroxide, potassium hydroxide, sodium hydride, and potassium phosphate; organic amine compounds, such as triethylamine, pyridine, and N-methylmorpholine; etc. One of these or a combination of two or more thereof may be used.

The solvent used in this event is not particularly limited, as long as the solvent is inactive in the reaction. Examples of the solvent include ether-based solvents, such as diethyl ether, tetrahydrofuran, and dioxane; aromatic solvents, such as benzene, toluene, and xylene; acetonitrile, dimethylsulfoxide, N,N-dimethylformamide, N-methylpyrrolidone, water, etc. One of these or a mixture thereof can be used.

The polymer can be collected through the same reaction and collection methods as those described in the paragraphs for the synthesis method of the polymer having a repeating unit shown by the general formula (1) under the section of Polymer Production Method.

In the preparation of the polymer for an organic film material obtained according to this method, various halides, tosylates, and mesylates can be used alone or in combination, depending on the required performances. For example, compounds having a side chain structure for enhancing planarizing property, a rigid aromatic ring structure for enhancing etching resistance and heat resistance, and so forth can be combined at a certain ratio. Thus, a material for forming an organic film, which uses these polymers, can achieve all of filling property, planarizing property, and etching resistance at high levels.

As described above, the inventive polymer for an organic film material an enables the organic film material to exhibit high etching resistance and excellent twisting resistance.

<Material for Forming Organic Film>

The present invention further provides a material for forming an organic film, containing: (A) the inventive polymer for an organic film material described above; and (B) an organic solvent. Note that, in the inventive material for forming an organic film, one kind of the inventive polymer for an organic film material can be used, or several kinds of the inventive polymer can be used in combination.

[(B) Organic Solvent]

The organic solvent usable in the inventive material for forming an organic film is not particularly limited, as long as the organic solvent dissolves the polymer (base polymer) and, if any, an acid generator, a crosslinking agent, and other additives to be described later, for example. Specifically, a solvent having a boiling point of lower than 180° C. can be used, such as solvents disclosed in paragraphs [0091] to [0092] of JP 2007-199653 A. Above all, it is preferable to use propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, 2-heptanone, cyclopentanone, cyclohexanone, and a mixture of two or more thereof. The organic solvent is blended in an amount of preferably 200 to 10,000 parts, more preferably 300 to 5,000 parts, based on 100 parts of the polymer (A).

Such a material for forming an organic film can be applied by spin coating. Since the inventive polymer for an organic film material as described above is incorporated, the material for forming an organic film enables all of favorable dry etching resistance, high heat resistance, and high filling and planarizing properties.

Further, in the inventive material for forming an organic film, it is also possible to add, as a component of the organic solvent, a high-boiling-point solvent having a boiling point of 180° C. or higher to the above-described solvent having a boiling point of lower than 180° C. (a mixture of a solvent having a boiling point of lower than 180° C. and a solvent having a boiling point of 180° C. or higher). The high-boiling-point organic solvent is not particularly limited to hydrocarbons, alcohols, ketones, esters, ethers, chlorinated solvents, and so forth, as long as the high-boiling-point organic solvent is capable of dissolving the polymer for an organic film material. Specific examples of the high-boiling-point organic solvent include 1-octanol, 2-ethylhexanol, 1-nonanol, 1-decanol, 1-undecanol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, glycerin, n-nonyl acetate, ethylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monohexyl ether, diethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butylmethyl ether, triethylene glycol dimethyl ether, triethylene glycol monomethyl ether, triethylene glycol-n-butyl ether, triethylene glycol butylmethyl ether, triethylene glycol diacetate, tetraethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol mono-n-propyl ether, tripropylene glycol mono-n-butyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triacetin, propylene glycol diacetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol methyl-n-propyl ether, dipropylene glycol methyl ether acetate, 1,4-butanediol diacetate, 1,3-butylene glycol diacetate, 1,6-hexanediol diacetate, triethylene glycol diacetate, γ-butyrolactone, dihexyl malonate, diethyl succinate, dipropyl succinate, dibutyl succinate, dihexyl succinate, dimethyl adipate, diethyl adipate, dibutyl adipate, etc. One or a mixture of these may be used.

The boiling point of the high-boiling-point solvent(s) may be appropriately selected according to the temperature at which the material for forming an organic film is heated. The boiling point of the high-boiling-point solvent(s) to be added is preferably 180° C. to 300° C., more preferably 200° C. to 300° C. Such boiling points prevent the evaporation rate at baking (heating) from becoming excessive, which would otherwise occur if the boiling point is too low. Thus, the boiling points can provide sufficient thermal flowability. Moreover, such boiling points are not too high, so that the high-boiling-point solvent(s) evaporate and do not remain in the film after baking; thus, the boiling points do not adversely affect the film physical properties, such as etching resistance.

Moreover, when the high-boiling-point solvent(s) are used, the high-boiling-point solvent(s) are blended in an amount of preferably 1 to 30 parts by mass based on 100 parts by mass of the solvent(s) having a boiling point of lower than 180° C. Such a formulation amount prevents a failure in providing sufficient thermal flowability during baking, which would otherwise occur if the formulation amount is too small. In addition, degradation of the film physical properties such as etching resistance is prevented, which would otherwise occur if the formulation amount is so large that the solvent(s) remain in the film.

Such a material for forming an organic film has thermal flowability imparted by adding the high-boiling-point solvent to the above-described material for forming an organic film. Thus, the resulting composition for forming an organic film has both high filling and planarizing properties.

[(C) Acid Generator]

In the inventive material for forming an organic film, an acid generator (C) can be added so as to further promote the curing reaction. The acid generator includes a material that generates an acid by thermal decomposition, and a material that generates an acid by light irradiation. Any of these can be added. Specifically, materials disclosed in paragraphs [0061] to [0085] of JP 2007-199653 A can be added, but the present invention is not limited thereto.

One kind of the acid generator can be used singly, or two or more kinds thereof can be used in combination. When an acid generator is added, the acid generator is added in an amount of preferably 0.05 to 50 parts, more preferably 0.1 to 10 parts, based on 100 parts of the polymer (A).

[(D) Surfactant]

To the inventive material for forming an organic film, a surfactant (D) can be added so as to enhance the coating property in spin coating. As the surfactant, for example, those disclosed in [0142] to [0147] of JP 2009-269953 A can be used. When a surfactant is added, the surfactant is added in an amount of preferably 0.01 to 10 parts, more preferably 0.05 to 5 parts, based on 100 parts of the polymer (A).

[(E) Crosslinking Agent]

Moreover, to the inventive material for forming an organic film, a crosslinking agent (E) can also be added so as to increase the curability and to further suppress intermixing with an upper layer film. The crosslinking agent is not particularly limited, and known various types of crosslinking agents can be widely used. Examples thereof can include melamine-based crosslinking agents, glycoluril-based crosslinking agents, benzoguanamine-based crosslinking agents, urea-based crosslinking agents, β-hydroxyalkylamide-based crosslinking agents, isocyanurate-based crosslinking agents, aziridine-based crosslinking agents, oxazoline-based crosslinking agents, and epoxy-based crosslinking agents.

Specific examples of the melamine-based crosslinking agents include hexamethoxymethylated melamine, hexabutoxymethylated melamine, alkoxy- and/or hydroxy-substituted derivatives thereof, and partial self-condensates thereof. Specific examples of the glycoluril-based crosslinking agents include tetramethoxymethylated glycoluril, tetrabutoxymethylated glycoluril, alkoxy- and/or hydroxy-substituted derivatives thereof, and partial self-condensates thereof. Specific examples of the benzoguanamine-based crosslinking agents include tetramethoxymethylated benzoguanamine, tetrabutoxymethylated benzoguanamine, alkoxy- and/or hydroxy-substituted derivatives thereof, and partial self-condensates thereof. Specific examples of the urea-based crosslinking agents include dimethoxymethylated dimethoxyethyleneurea, alkoxy- and/or hydroxy-substituted derivatives thereof, and partial self-condensates thereof. A specific example of the p-hydroxyalkylamide-based crosslinking agents includes N,N,N′,N′-tetra(2-hydroxyethyl)adipic acid amide. Specific examples of the isocyanurate-based crosslinking agents include triglycidyl isocyanurate and triallyl isocyanurate. Specific examples of the aziridine-based crosslinking agents include 4,4′-bis(ethyleneiminocarbonylamino)diphenylmethane and 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate]. Specific examples of the oxazoline-based crosslinking agents include 2,2′-isopropylidene bis(4-benzyl-2-oxazoline), 2,2′-isopropylidene bis(4-phenyl-2-oxazoline), 2,2′-methylenebis4,5-diphenyl-2-oxazoline, 2,2′-methylenebis-4-phenyl-2-oxazoline, 2,2′-methylenebis-4-tert-butyl-2-oxazoline, 2,2′-bis(2-oxazoline), 1,3-phenylenebis(2-oxazoline), 1,4-phenylenebis(2-oxazoline), and a 2-isopropenyl oxazoline copolymer. Specific examples of the epoxy-based crosslinking agents include diglycidyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, poly(glycidyl methacrylate), trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether. When a crosslinking agent is added, the crosslinking agent is added in an amount of preferably 1 to 100 parts, more preferably 5 to 50 parts, based on 100 parts of the polymer (A).

[(F) Plasticizer]

Further, to the inventive material for forming an organic film, a plasticizer (F) can be added so as to further enhance planarizing and filling properties. The plasticizer is not particularly limited, and known various types of plasticizers can be widely used. Examples thereof can include low-molecular-weight compounds, such as phthalic acid esters, adipic acid esters, phosphoric acid esters, trimellitic acid esters, and citric acid esters; and polymers, such as polyethers, polyesters, and polyacetal-based polymers disclosed in JP 2013-253227 A. When a plasticizer is added, the plasticizer is added in an amount of preferably 1 to 100 parts, more preferably 5 to 30 parts, based on 100 parts of the polymer (A).

Further, like the plasticizer, as an additive for imparting the filling and planarizing properties to the inventive material for forming an organic film, it is preferable to use, for example, liquid additives having polyethylene glycol or polypropylene glycol structure, or thermo-decomposable polymers having a weight loss ratio of 40 mass % or more between 30° C. and 250° C. and a weight-average molecular weight of 300 to 200,000. The thermo-decomposable polymers preferably contain a repeating unit having an acetal structure shown by the following general formula (DP1) or (DP1a).

In the formula, R₆ represents a hydrogen atom or a saturated or unsaturated monovalent organic group which has 1 to 30 carbon atoms and may be substituted. Y₁ represents a saturated or unsaturated divalent organic group having 2 to 30 carbon atoms.

In the formula, R_(6a) represents an alkyl group having 1 to 4 carbon atoms. Y^(a) represents a saturated or unsaturated divalent hydrocarbon group which has 4 to 10 carbon atoms and may have an ether bond. “n” represents an average repeating unit number of 3 to 500.

[(G) Other Components]

The inventive material for forming an organic film may be further blended with a different compound or polymer. The blend compound or blend polymer mixed with the inventive material for forming an organic film serves to improve the film formability by spin-coating and/or the filling property for a stepped substrate.

Examples of such materials include novolak resins of phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 2-phenylphenol, 3-phenylphenol, 4-phenylphenol, 3,5-diphenylphenol, 2-naphthylphenol, 3-naphthylphenol, 4-naphthylphenol, 4-tritylphenol, resorcinol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, catechol, 4-tert-butylcatechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-methoxy-5-methylphenol, 2-tert-butyl-5-methylphenol, pyrogallol, thymol, isothymol, 4,4′-(9H-fluorene-9-ylidene)bisphenol, 2,2′dimethyl-4,4′-(9H-fluorene-9-ylidene)bisphenol, 2,2′diallyl-4,4′-(9H-fluorene-9-ylidene)bisphenol, 2,2′difluoro-4,4′-(9H-fluorene-9-ylidene)bisphenol, 2,2′diphenyl-4,4′-(9H-fluorene-9-ylidene)bisphenol, 2,2′dimethoxy-4,4′-(9H-fluorene-9-ylidene)bisphenol, 2,3,2′,3′-tetrahydro-(1,1′)-spirobiindene-6,6′-diol, 3,3,3′,3′-tetramethyl-2,3,2′,3′-tetrahydro-(1,1′)-spirobiindene-6,6′-diol, 3,3,3′,3′,4,4′-hexamethyl-2,3,2′,3′-tetrahydro-(1,1′)-spirobiindene-6,6′-diol, 2,3,2′,3′-tetrahydro-(1,1′)-spirobiindene-5,5′-diol, 5,5′-dimethyl-3,3,3′,3′-tetramethyl-2,3,2′,3′-tetrahydro-(1,1′)-spirobiindene-6,6′-diol, 1-naphthol, 2-naphthol, 2-methyl-1-naphthol, 4-methoxy-1-naphthol, and 7-methoxy-2-naphthol, dihydroxynaphthalenes such as 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, and 2,6-dihydroxynaphthalene, methyl 3-hydroxynaphthalene-2-carboxylate, indene, hydroxyindene, benzofuran, hydroxyanthracene, acenaphthylene, biphenyl, bisphenol, trisphenol, dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, norbornadiene, 5-vinylnorborna-2-ene, α-pinene, β-pinene, limonene, etc.; and polyhydroxystyrene, polystyrene, polyvinylnaphthalene, polyvinylanthracene, polyvinylcarbazole, polyindene, polyacenaphthylene, polynorbornene, polycyclodecene, polytetracyclododecene, polynortricyclene, poly(meth)acrylate, and copolymers thereof. It is also possible to blend a naphthol dicyclopentadiene copolymer disclosed in JP 2004-205685 A, a fluorene bisphenol novolak resin disclosed in JP 2005-128509 A, an acenaphthylene copolymer disclosed in JP 2005-250434 A, fullerene having a phenol group disclosed in JP 2006-227391 A, a bisphenol compound and a novolak resin thereof disclosed in JP 2006-293298 A, a novolak resin of an adamantane phenol compound disclosed in JP 2006-285095 A, a bisnaphthol compound and a novolak resin thereof disclosed in JP 2010-122656 A, a fullerene resin compound disclosed in JP 2008-158002 A, etc.

The blendable compound or blendable polymer is blended in an amount of preferably 0 to 1,000 parts by mass, more preferably 0 to 500 parts by mass, based on 100 parts by mass of the inventive material for forming an organic film.

Note that one kind of the inventive material for forming an organic film can be used, or two or more kinds thereof can be used in combination. The material for forming an organic film can be used as an organic film material or a planarizing material for manufacturing a semiconductor device.

Moreover, the inventive material for forming an organic film is quite useful as an organic film material for multilayer resist processes, such as a two-layer resist process, a three-layer resist process using a silicon-containing underlayer film, and a four-layer resist process using a silicon-containing inorganic hard mask underlayer film and an organic antireflective coating film.

(Method for Forming Organic Film)

The present invention provides a method for forming an organic film by using the above-described material for forming an organic film. The resulting organic film can serve as an organic film in a multilayer resist film used in lithography or a planarizing film for manufacturing a semiconductor.

In the method for forming an organic film by using the inventive material for forming an organic film, a substrate to be processed is coated with the material for forming an organic film by a spin coating method etc. By employing a method like spin coating method, favorable filling property can be obtained. After the spin coating, the solvent is evaporated, and baking (heating) is performed to promote the crosslinking reaction, thereby preventing the mixing with a resist upper layer film or a resist underlayer film. The baking is preferably performed at 100° C. or more and 600° C. or less within 10 to 600 seconds, more preferably at 200° C. or more and 500° C. or less within 10 to 300 seconds. In considering the influences of device damage and wafer deformation, the upper limit of the heating temperature in lithographic wafer process is preferably 600° C. or less, more preferably 500° C. or less.

Moreover, in the method for forming an organic film by using the inventive material for forming an organic film, after a substrate to be processed is coated with the inventive material for forming an organic film by the spin coating method or the like as described above, an organic film can be formed by curing the material for forming an organic film by baking in an atmosphere with an oxygen concentration of 0.1% or more and 21% or less.

A sufficiently cured film can be obtained by baking the inventive material for forming an organic film in such an oxygen atmosphere. The atmosphere during the baking may be in air. Nevertheless, it is preferable to introduce an inert gas such as N₂, Ar, or He to reduce oxygen amount from the viewpoint of preventing oxidation of the organic film. To prevent the oxidation, the oxygen concentration needs to be controlled, and is preferably 1000 ppm or less, more preferably 100 ppm or less. Preventing the oxidation of the organic film during baking is preferable because an increase in absorption and a decrease in etching resistance are prevented.

Such a method for forming an organic film by using the inventive material for forming an organic film makes it possible to obtain a flat cured film regardless of unevenness of a substrate to be processed, because of the excellent filling and planarizing properties. Accordingly, the method is quite useful in forming a flat cured film on a substrate to be processed which has a structure or step with a height of 30 nm or more.

Note that the thickness of the organic film such as a planarizing film for manufacturing a semiconductor device is appropriately determined and preferably 30 to 20,000 nm, particularly preferably 50 to 15,000 nm.

(Patterning Processes)

The present invention provides a patterning process according to a three-layer resist process using such a material for forming an organic film as described above. The patterning process is a patterning process for forming a pattern in a substrate to be processed, and includes at least:

forming an organic film by using the inventive material for forming an organic film on a substrate to be processed;

forming a silicon-containing resist underlayer film by using a resist underlayer film material containing silicon atoms on the organic film;

forming a resist upper layer film by using a photoresist composition as a resist upper layer film material on the silicon-containing resist underlayer film, so that a multilayer resist film is formed;

subjecting a pattern circuit region of the resist upper layer film to exposure and then development with a developer to form a resist pattern in the resist upper layer film;

transferring the pattern to the silicon-containing resist underlayer film by etching while using the obtained resist pattern as an etching mask;

transferring the pattern to the organic film by etching while using the obtained pattern in the silicon-containing resist underlayer film as an etching mask; and

further transferring the pattern to the substrate to be processed by etching while using the obtained organic film pattern as an etching mask.

The silicon-containing resist underlayer film in this three-layer resist process exhibits resistance to etching with an oxygen gas or a hydrogen gas. Hence, when the organic film is dry-etched using the silicon-containing resist underlayer film as a mask in the three-layer resist process, the dry etching is performed preferably with an etching gas mainly containing an oxygen gas or a hydrogen gas.

As the silicon-containing resist underlayer film in the three-layer resist process, a polysiloxane-based underlayer film is also preferably used. The silicon-containing resist underlayer film having antireflective effect can suppress the reflection. Particularly, for 193-nm light exposure, a material containing many aromatic groups and having high etching selectivity relative to the substrate is used as an organic film, so that the k-value and thus the substrate reflection are increased. Meanwhile, the reflection can be suppressed by imparting absorption to the silicon-containing resist underlayer film so as to have an appropriate k-value, and the substrate reflection can be reduced to 0.5% or less. As the silicon-containing resist underlayer film having antireflective effect, a polysiloxane is preferably used which has anthracene for 248-nm and 157-nm light exposure, or a phenyl group or a light-absorbing group having a silicon-silicon bond for 193-nm light exposure in a pendant structure, and which is crosslinked by an acid or heat.

Moreover, the present invention is suitable for a four-layer resist process using an organic antireflective coating film. In this case, a semiconductor-device circuit pattern can be formed in a substrate by a patterning process including at least:

forming an organic film by using the inventive material for forming an organic film on a substrate to be processed;

forming a silicon-containing resist underlayer film by using a silicon-containing resist underlayer film material on the organic film;

forming an organic antireflective coating film on the silicon-containing resist underlayer film;

forming a resist upper layer film by using a photoresist composition as a resist upper layer film material on the organic antireflective coating film, so that a multilayer resist film is formed;

subjecting a pattern circuit region of the resist upper layer film to exposure and then development with a developer to form a resist pattern in the resist upper layer film;

transferring the pattern to the organic antireflective coating film and the silicon-containing resist underlayer film by etching while using the obtained resist pattern as an etching mask;

transferring the pattern to the organic film by etching while using the obtained pattern in the silicon-containing resist underlayer film as an etching mask; and

further transferring the pattern to the substrate to be processed by etching the substrate to be processed while using the obtained organic film pattern as an etching mask.

Alternatively, an inorganic hard mask may be formed instead of the silicon-containing resist underlayer film. In this case, a semiconductor-device circuit pattern can be formed in a substrate by a patterning process including at least:

forming an organic film by using the inventive material for forming an organic film on a substrate to be processed;

forming an inorganic hard mask selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the organic film;

forming a resist upper layer film by using a photoresist composition as a resist upper layer film material on the inorganic hard mask;

subjecting a pattern circuit region of the resist upper layer film to exposure and then development with a developer to form a resist pattern in the resist upper layer film;

transferring the pattern to the inorganic hard mask by etching while using the obtained resist pattern as an etching mask;

transferring the pattern to the organic film by etching while using the obtained inorganic hard mask pattern as an etching mask; and

further transferring the pattern to the substrate to be processed by etching while using the obtained organic film pattern as an etching mask.

As described above, when an inorganic hard mask is formed on an organic film, a silicon oxide film, a silicon nitride film, and a silicon oxynitride film (SiON film) can be formed by a CVD method, an ALD method, etc. The method for forming a silicon nitride film is described, for example, in JP 2002-334869 A and WO 2004/066377 A1. The film thickness of the inorganic hard mask is preferably 5 to 200 nm, more preferably 10 to 100 nm. As the inorganic hard mask, a SiON film is most preferably used which is effective as an antireflective film. When the SiON film is formed, the substrate temperature reaches 300 to 500° C. Hence, the organic film needs to withstand the temperature of 300 to 500° C. Since the material for forming an organic film used in the present invention has high heat resistance and can withstand high temperatures of 300° C. to 500° C., this enables the combination of the inorganic hard mask formed by a CVD method or an ALD method with the organic film formed by a spin coating method.

Furthermore, the present invention is suitable for a four-layer resist process using an organic antireflective coating film. In this case, a semiconductor-device circuit pattern can be formed in a substrate by a patterning process including at least:

forming an organic film by using the inventive material for forming an organic film on a substrate to be processed;

forming an inorganic hard mask selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the organic film;

forming an organic antireflective coating film on the inorganic hard mask;

forming a resist upper layer film by using a photoresist composition as a resist upper layer film material on the organic antireflective coating film, so that a multilayer resist film is formed;

subjecting a pattern circuit region of the resist upper layer film to exposure and then development with a developer to form a resist pattern in the resist upper layer film;

transferring the pattern to the organic antireflective coating film and the inorganic hard mask by etching while using the obtained resist pattern as an etching mask;

transferring the pattern to the organic film by etching while using the obtained inorganic hard mask pattern as an etching mask; and

further transferring the pattern to the substrate to be processed by etching while using the obtained organic film pattern as an etching mask.

Although a photoresist film may be formed as a resist upper layer film on an inorganic hard mask, it is also possible to form an organic antireflective coating film (BARC) on the inorganic hard mask by spin coating and then form the photoresist film on the BARC as described above. Particularly, when a SiON film is used as the inorganic hard mask, two antireflective films including the SION film and the BARC make it possible to suppress the reflection even in immersion exposure at a high NA exceeding 1.0. Another merit of the BARC formation is having an effect of reducing footing of the photoresist pattern immediately above the SiON film.

The resist upper layer film in the 3-layer resist process may be a positive type or a negative type, and generally-used photoresist compositions can be employed. After spin-coating of the photoresist composition, pre-baking is performed preferably at 60 to 180° C. for 10 to 300 seconds. Then, light exposure, post-exposure bake (PEB), and development are performed according to conventional methods to obtain the resist pattern. Note that the thickness of the resist upper layer film is not particularly limited, but is preferably 30 to 500 nm, and 50 to 400 nm is particularly preferable.

Additionally, examples of exposure light can include a high-energy beam with a wavelength of 300 nm or less, specifically, excimer laser of 248 nm, 193 nm, and 157 nm, soft X-ray of 3 to 20 nm, electron beam, X-ray, etc.

A pattern is formed in the resist upper layer film by a method of preferably a photolithography with a wavelength of 10 nm or more and 300 nm or less, a direct drawing with electron beam, nanoimprinting, or a combination thereof.

Moreover, as the development method in the patterning processes, alkaline development or organic solvent development is preferably employed.

Next, etching is performed using the obtained resist pattern as a mask. In the three-layer resist process, the silicon-containing resist underlayer film or the inorganic hard mask can be etched using a fluorocarbon-based gas and using the upper layer resist pattern as the mask. Thereby, a silicon-containing resist underlayer film pattern or an inorganic hard mask pattern is formed.

Next, using the obtained silicon-containing resist underlayer film pattern or inorganic hard mask pattern as a mask, the organic film is processed by etching.

Subsequently, the substrate to be processed can be etched according to a conventional method. For example, the substrate to be processed made of SiO₂, SiN, or silica low-dielectric insulating film is etched mainly with a fluorocarbon-based gas; and the substrate to be processed made of p-Si, Al, or W is etched mainly with a chlorine- or bromine-based gas. When the substrate is processed by etching with a fluorocarbon-based gas, the silicon-containing resist underlayer film pattern in the three-layer resist process is removed when the substrate is processed. Meanwhile, when the substrate is etched with a chlorine- or bromine-based gas, the silicon-containing resist underlayer film pattern needs to be removed by additional dry etching with a fluorocarbon-based gas after the substrate processing.

The organic film obtained from the inventive material for forming an organic film is characterized by excellent etching resistance when the substrate to be processed is etched as described above.

Note that the substrate to be processed is not particularly limited, and examples thereof include: substrates made of Si, α-Si, p-Si, SiO₂, SiN, SiON, W, TiN, Al, or the like; these substrates coated with a layer to be processed; etc. Examples of the layer to be processed include: various Low-k films made of Si, SiO₂, SiON, SiN, p-Si, α-Si, W, W—Si, Al, Cu, Al—Si, or the like; and stopper films thereof. The layer can be formed to have a thickness of generally 50 to 10,000 nm, particularly 100 to 5,000 nm. Note that when the layer to be processed is formed, the substrate and the layer to be processed are formed from different materials.

As the substrate to be processed, it is preferable to use a semiconductor device substrate or the semiconductor device substrate coated with any of a metal film, a metal carbide film, a metal oxide film, a metal nitride film, a metal oxycarbide film, and a metal oxynitride film. More specifically, although the substrate to be processed is not particularly limited, examples thereof include substrates made of Si, α-Si p-Si, SiO₂, SiN, SiON, W, TiN, Al, or the like; these substrates coated with any film of the aforementioned metal films, or the like as a layer to be processed; etc.

Examples of the layer to be processed include various Low-k films made of Si, SiO₂, SION, SiN, p-Si, α-Si, W, W—Si, Al, Cu, Al—Si, or the like; and stopper films thereof. The layer can be formed to have a thickness of generally 50 to 10,000 nm, particularly 100 to 5,000 nm. Note that when the layer to be processed is formed, the substrate and the layer to be processed are formed from different materials.

Note that the metal constituting the substrate to be processed is preferably silicon, titanium, tungsten, hafnium, zirconium, chromium, germanium, copper, silver, gold, aluminum, indium, gallium, arsenic, palladium, iron, tantalum, iridium, cobalt, manganese, molybdenum, ruthenium, or an alloy thereof.

Moreover, as the substrate to be processed, it is preferable to use a substrate to be processed which has a structure or step with a height of 30 nm or more.

Hereinbelow, an example of the three-layer resist process will be specifically described with reference to FIG. 1. As shown in FIG. 1 (A), in the three-layer resist process, an organic film 3 is formed by using the inventive material for forming an organic film on a layer 2 to be processed that has been stacked on a substrate 1. Then, a silicon-containing resist underlayer film 4 is formed, and a resist upper layer film 5 is formed thereon.

Next, as shown in FIG. 1 (B), a predetermined portion 6 of the resist upper layer film 5 is exposed to light, followed by PEB and development to form a resist pattern 5 a (FIG. 1 (C)). While using the obtained resist pattern 5 a as a mask, the silicon-containing resist underlayer film 4 is etched with a CF-based gas. Thereby, a silicon-containing resist underlayer film pattern 4 a is formed (FIG. 1 (D)). After the resist pattern 5 a is removed, the organic film 3 is etched with oxygen plasma while using the obtained silicon-containing resist underlayer film pattern 4 a as a mask. Thereby, an organic film pattern 3 a is formed (FIG. 1 (E)). Further, after the silicon-containing resist underlayer film pattern 4 a is removed, the layer 2 to be processed is etched while using the organic film pattern 3 a as a mask. Thus, a pattern 2 a is formed (FIG. 1 (F)).

When an inorganic hard mask is used, the inorganic hard mask is formed in place of the silicon-containing resist underlayer film 4. When a BARC is formed, the BARC layer is provided between the silicon-containing resist underlayer film 4 and the resist upper layer film 5. The etching of the BARC starts before the etching of the silicon-containing resist underlayer film 4, but these etchings may be performed continuously. Alternatively, after the BARC is etched alone, the etching apparatus is changed, for example, and then the silicon-containing resist underlayer film 4 may be etched.

As described above, the inventive patterning processes make it possible to precisely form a fine pattern in a substrate to be processed in multilayer resist processes.

EXAMPLE

Hereinafter, the present invention will be more specifically described with reference to Synthesis Examples, Examples, and Comparative Examples. Nevertheless, the present invention is not limited thereto. Note that regarding molecular weight and dispersity, gel permeation chromatography (GPC) was performed using tetrahydrofuran as an eluent to determine weight-average molecular weight (Mw) and number-average molecular weight (Mn) in terms of polystyrene, and dispersity (Mw/Mn) was obtained therefrom.

Synthesis Examples: Synthesis of Polymers for Organic Film Material

Polymers (A1) to (A11) used in a material for forming an organic film as well as Compounds (R1) and (R2) used in Comparative Examples were synthesized using the following Dial compounds (B1) to (B6), Fluorenols (C1) to (C4), and water or (D1) to (D3) as end-capping agents.

Diol Compounds:

Fluorenols:

End-Capping Agents:

Synthesis Example 1 Synthesis of Polymer (A1)

Under nitrogen atmosphere, 5.7 g of Diol compound (B1), 30.0 g of Fluorenol (C1), and 100 g of 1,2-dichloroethane were added together to prepare a homogeneous dispersion with an inner temperature of 50° C. Then, 15.4 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 6 hours. Further, 2.3 g of pure water was added and the reaction was allowed to proceed for another 3 hours. After completion of the reaction, the resultant was cooled to room temperature, mixed with 200 ml of MIBK (methyl isobutyl ketone), and washed six times with 100 ml of pure water. The organic layer was dried under reduced pressure. To the residue, 100 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was precipitated with 300 g of methanol. The precipitated crystal was separated by filtration, washed twice with 200 g of methanol, and collected. The collected crystal was vacuum dried at 70° C. Thus, (A1) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(A1): Mw=2700, Mw/Mn=1.58 Synthesis Example 2 Synthesis of Polymer (A2)

Under nitrogen atmosphere, 8.6 g of Diol compound (B5), 25.0 g of Fluorenol (C1), and 100 g of 1,2-dichloroethane were added together to prepare a homogeneous dispersion with an inner temperature of 50° C. Then, 12.9 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 6 hours. Further, 9.6 g of End-capping agent (D1) was added and the reaction was allowed to proceed for another 3 hours. After completion of the reaction, the resultant was cooled to room temperature, mixed with 300 ml of MIBK, and washed six times with 100 ml of pure water. The organic layer was dried under reduced pressure. To the residue, 100 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was precipitated with 350 g of methanol. The precipitated crystal was separated by filtration, washed twice with 200 g of methanol, and collected. The collected crystal was vacuum dried at 70° C. Thus, (A2) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(A2): Mw=3400, Mw/Mn=1.78 Synthesis Example 3 Synthesis of Polymer (A3)

Under nitrogen atmosphere, 5.4 g of Diol compound (B1), 30.0 g of Fluorenol (C2), and 100 g of 1,2-dichloroethane were added together to prepare a homogeneous dispersion with an inner temperature of 50° C. Then, 14.8 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 6 hours. Further, 2.2 g of pure water was added and the reaction was allowed to proceed for another 3 hours. After completion of the reaction, the resultant was cooled to room temperature, mixed with 200 ml of MIBK, and washed six times with 100 ml of pure water. The organic layer was dried under reduced pressure. To the residue, 100 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was precipitated with 300 g of methanol. The precipitated crystal was separated by filtration, washed twice with 200 g of methanol, and collected. The collected crystal was vacuum dried at 70° C. Thus, (A3) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(A3): Mw 3100, Mw/Mn=1.59 Synthesis Example 4 Synthesis of Polymer (A4)

Under nitrogen atmosphere, 7.9 g of Diol compound (B2), 30.0 g of Fluorenol (C2), and 100 g of 1,2-dichloroethane were added together to prepare a homogeneous dispersion with an inner temperature of 50° C. Then, 14.8 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 6 hours. Further, 9.1 g of End-capping agent (D2) was added and the reaction was allowed to proceed for another 3 hours. After completion of the reaction, the resultant was cooled to room temperature, mixed with 300 ml of MIBK, and washed six times with 100 ml of pure water. The organic layer was dried under reduced pressure. To the residue, 100 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was precipitated with 350 g of methanol. The precipitated crystal was separated by filtration, washed twice with 200 g of methanol, and collected. The collected crystal was vacuum dried at 70° C. Thus, (A4) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(A4): Mw=3200, Mw/Mn=1.51 Synthesis Example 5 Synthesis of Polymer (A5)

Under nitrogen atmosphere, 12.0 g of Diol compound (B6), 20.0 g of Fluorenol (C2), and 100 g of 1,2-dichloroethane were added together to prepare a homogeneous dispersion with an inner temperature of 50° C. Then, 9.9 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 6 hours. Further, 8.6 g of End-capping agent (D1) was added and the reaction was allowed to proceed for another 3 hours. After completion of the reaction, the resultant was cooled to room temperature, mixed with 300 ml of MIBK, and washed six times with 100 ml of pure water. The organic layer was dried under reduced pressure. To the residue, 100 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was precipitated with 350 g of methanol. The precipitated crystal was separated by filtration, washed twice with 200 g of methanol, and collected. The collected crystal was vacuum dried at 70° C. Thus, (A5) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(A5): Mw=3800, Mw/Mn=1.84 Synthesis Example 6 Synthesis of Polymer (A6)

Under nitrogen atmosphere, 7.9 g of Dial compound (B3), 30.0 g of Fluorenol (C3), and 100 g of 1,2-dichloroethane were added together to prepare a homogeneous dispersion with an inner temperature of 50° C. Then, 14.8 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 6 hours. Further, 2.2 g of pure water was added and the reaction was allowed to proceed for another 3 hours. After completion of the reaction, the resultant was cooled to room temperature, mixed with 200 ml of MIBK, and washed six times with 100 ml of pure water. The organic layer was dried under reduced pressure. To the residue, 100 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was precipitated with 300 g of methanol. The precipitated crystal was separated by filtration, washed twice with 200 g of methanol, and collected. The collected crystal was vacuum dried at 70° C. Thus, (A6) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(A6): Mw=2900, Mw/Mn=1.59 Synthesis Example 7 Synthesis of Polymer (A7)

Under nitrogen atmosphere, 7.9 g of Diol compound (B4), 30.0 g of Fluorenol (C3), and 100 g of 1,2-dichloroethane were added together to prepare a homogeneous dispersion with an inner temperature of 50° C. Then, 14.8 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 6 hours. Further, 4.4 g of End-capping agent (D3) was added and the reaction was allowed to proceed for another 3 hours. After completion of the reaction, the resultant was cooled to room temperature, mixed with 300 ml of MIBK, and washed six times with 100 ml of pure water. The organic layer was dried under reduced pressure. To the residue, 100 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was precipitated with 350 g of methanol. The precipitated crystal was separated by filtration, washed twice with 200 g of methanol, and collected. The collected crystal was vacuum dried at 70° C. Thus, (A7) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(A7): Mw=3200, Mw/Mn=1.67 Synthesis Example 8 Synthesis of Polymer (A8)

Under nitrogen atmosphere, 9.4 g of Diol compound (B5), 25.0 g of Fluorenol (C3), and 100 g of 1,2-dichloroethane were added together to prepare a homogeneous dispersion with an inner temperature of 50° C. Then, 12.3 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 6 hours. Further, 6.1 g of End-capping agent (D1) was added and the reaction was allowed to proceed for another 3 hours. After completion of the reaction, the resultant was cooled to room temperature, mixed with 300 ml of MIBK, and washed six times with 100 ml of pure water. The organic layer was dried under reduced pressure. To the residue, 100 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was precipitated with 350 g of methanol. The precipitated crystal was separated by filtration, washed twice with 200 g of methanol, and collected. The collected crystal was vacuum dried at 70° C. Thus, (A8) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(A8): Mw=3000, Mw/Mn=1.71 Synthesis Example 9 Synthesis of Polymer (A9)

Under nitrogen atmosphere, 6.6 g of Diol compound (B3), 30.0 g of Fluorenol (C4), and 100 g of 1,2-dichloroethane were added together to prepare a homogeneous dispersion with an inner temperature of 50° C. Then, 12.3 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 6 hours. Further, 3.6 g of End-capping agent (D3) was added and the reaction was allowed to proceed for another 3 hours. After completion of the reaction, the resultant was cooled to room temperature, mixed with 300 ml of MIBK, and washed six times with 100 ml of pure water. The organic layer was dried under reduced pressure. To the residue, 100 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was precipitated with 350 g of methanol. The precipitated crystal was separated by filtration, washed twice with 200 g of methanol, and collected. The collected crystal was vacuum dried at 70° C. Thus, (A9) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(A9): Mw=3500, Mw/Mn=1.74 Synthesis Example 10 Synthesis of Polymer (A10)

Under nitrogen atmosphere, 6.6 g of Diol compound (B4), 30.0 g of Fluorenol (C4), and 100 g of 1,2-dichloroethane were added together to prepare a homogeneous dispersion with an inner temperature of 50° C. Then, 12.3 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 6 hours. Further, 1.8 g of pure water was added and the reaction was allowed to proceed for another 3 hours. After completion of the reaction, the resultant was cooled to room temperature, mixed with 200 ml of MIBK, and washed six times with 100 ml of pure water. The organic layer was dried under reduced pressure. To the residue, 100 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was precipitated with 300 g of methanol. The precipitated crystal was separated by filtration, washed twice with 200 g of methanol, and collected. The collected crystal was vacuum dried at 70° C. Thus, (A10) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(A10): Mw=2900, Mw/Mn=1.53 Synthesis Example 11 Synthesis of Polymer (A11)

Under nitrogen atmosphere, 21.9 g of Diol compound (B6), 20.0 g of Fluorenol (C4), and 100 g of 1,2-dichloroethane were added together to prepare a homogeneous dispersion with an inner temperature of 50° C. Then, 8.2 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 9 hours. After completion of the reaction, the resultant was cooled to room temperature, mixed with 300 ml of MIBK, and washed six times with 100 ml of pure water. The organic layer was dried under reduced pressure. To the residue, 100 g of DMF was added and a homogeneous solution was prepared. To this solution, 8.1 g of potassium carbonate was added and a homogeneous dispersion with the inner temperature of 50° C. was prepared under nitrogen atmosphere. Then, 5.2 g of propargyl bromide was slowly added thereto, and the reaction was allowed to proceed with the inner temperature of 50° C. for 8 hours. To the reaction solution, 300 ml of methyl isobutyl ketone and 200 g of pure water were added to dissolve deposited salt. Thereafter, the separated aqueous layer was removed. Further, after the organic layer was washed six times with 100 g of a 3% nitric acid aqueous solution and 100 g of pure water, the organic layer was dried under reduced pressure. To the residue, 150 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was precipitated with 300 g of methanol. The precipitated crystal was separated by filtration, washed twice with 200 g of methanol, and collected. The collected crystal was vacuum dried at 70° C. Thus, Compound (A11) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(A11): Mw=3900, Mw/Mn=2.03 Synthesis Example 12 Synthesis of Compound (R1) for Comparative Examples

Under nitrogen atmosphere, a homogeneous solution with a liquid temperature of 80° C. was prepared from 10.0 g of Diol compound (B6), 13.8 g of 9-ethynyl-9-fluorenol, 14.1 g of trimethyl orthoformate, and 250 g of 1,2-dichloroethane. Then, 3.4 g of pyridinium p-toluenesulfonate was added thereto, and the reaction was allowed to proceed with the liquid temperature of 80° C. for 12 hours. The resultant was cooled to room temperature and then mixed with 300 ml of MIBK. After the organic layer was washed five times with 100 g of pure water, the organic layer was dried under reduced pressure. To the residue, 50 g of THF was added and a homogeneous solution was prepared. Subsequently, a crystal was deposited with 200 g of methanol. The precipitated crystal was separated by filtration and dried under reduced pressure. Thus, Compound (R1) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(R1): Mw=900, Mw/Mn=1.04 Synthesis Example 13 Synthesis of Compound (R2) for Comparative Examples

Under nitrogen atmosphere, a homogeneous solution with a liquid temperature of 70° C. was prepared from 80 g of 2,7-dipropargyloxynaphthalene, 22 g of a 37% formalin solution, and 250 g of 1,2-dichloroethane. Then, 5 g of methanesulfonic acid was slowly added thereto, and the reaction was allowed to proceed with the liquid temperature of 80° C. for 12 hours. The resultant was cooled to room temperature and then mixed with 500 ml of MIBK. After the organic layer was washed five times with 200 g of pure water, the organic layer was dried under reduced pressure. To the residue, 300 g of THF was added and a homogeneous solution was prepared. Subsequently, the polymer was reprecipitated with 2000 g of hexane. The precipitated polymer was separated by filtration and dried under reduced pressure. Thus, Compound (R2) was obtained.

When the weight-average molecular weight (Mw) and dispersity (Mw/Mn) were determined by GPC, the following results were obtained.

(R2): Mw=2900, Mw/Mn=1.57

Tables 1 to 3 list the results of Mw and Mw/Mn of Polymers (A1) to (A11) used in Examples and Compounds (R1) and (R2) used in Comparative Examples.

TABLE 1 Synthesis Example Polymer Mw Mw/Mn 1

2700 1.58 2

3400 1.78 3

3100 1.59 4

3200 1.51

TABLE 2 Synthesis Example Polymer Mw Mw/Mn 5

3800 1.84 6

2900 1.59 7

3200 1.67 8

3000 1.71

TABLE 3 Synthesis Example Polymer Mw Mw/Mn  9

3500 1.74 10

2900 1.53 11

3900 2.03 12

 900 1.04 13

2900 1.57

Preparation of Materials (UDL-1 to -17, Comparative UDL-1 to -2) for Forming Organic Film

According to proportions shown in Table U, the polymers (A1) to (A11), (R1) and (R2), and an acid generator (AG) were dissolved using propylene glycol monomethyl ether acetate (PGMEA) containing 0.1 mass % PF-6320 (manufactured by OMNOVA Solutions Inc.) and optionally a high-boiling-point solvent of (S1) 1,6-diacetoxyhexane: boiling point of 260° C. or (S2) tripropylene glycol monomethyl ether: boiling point of 242° C. The resulting solutions were filtered through a 0.1-μm filter made of a fluorinated resin. Thus, materials (UDL-1 to -17, Comparative UDL-1 to -2) for forming an organic film were prepared.

TABLE 4 Material Polymer High-boiling- for forming or compound Acid generator point solvent PGMEA organic film (parts by mass) (parts by mass) (parts by mass) (parts by mass) UDL-1 A1 (10) AG (0.3) — 90 UDL-2 A2 (10) — — 90 UDL-3 A3 (10) AG (0.3) — 90 UDL-4 A4 (10) AG (0.3) — 90 UDL-5 A5 (10) — — 90 UDL-6 A6 (10) AG (0.3) — 90 UDL-7 A7 (10) — — 90 UDL-8 A8 (10) — — 90 UDL-9 A9 (10) — — 90 UDL-10 A10 (10)  AG (0.3) — 90 UDL-11 A11 (10)  — — 90 UDL-12 A3 (10) AG (0.3) S2 (10) 80 UDL-13 A5 (10) — S1 (10) 80 UDL-14 A6 (10) AG (0.3) S2 (10) 80 UDL-15 A7 (10) — S1 (10) 80 UDL-16 A9 (10) — S1 (10) 80 UDL-17 A11 (10)  — S2 (10) 80 Comparative R1 (10) — — 90 UDL-1 Comparative R2 (10) — — 90 UDL-2

The structural formula of the acid generator (AG) thus used is shown below.

Example 1: Solvent Resistance Measurement (Examples 1-1 to 1-17, Comparative Examples 1-1 to 1-2)

UDL-1 to -17 and Comparative UDL-1 to -2 prepared above were respectively applied onto silicon substrates, and baked in the atmosphere at 350° C. for 60 seconds. Then, the film thicknesses were measured. A PGMEA solvent was dispensed on each film and allowed to stand for 30 seconds. The resultant was spin dried and baked at 100° C. for 60 seconds to evaporate the PGMEA. The film thickness was measured to find the film thicknesses before and after the PGMEA treatment. The film thickness after the film formation and the film thickness after the PGMEA treatment were used to determine a film remaining ratio. Table 5 shows the result.

TABLE 5 Film Film thickness thickness Material after film after PGMEA b/a × for forming formation: treatment: 100 organic film a (Å) b (Å) (%) Example 1-1 UDL-1 1990 1990 100.0 Example 1-2 UDL-2 1991 1989 99.9 Example 1-3 UDL-3 2002 2000 99.9 Example 1-4 UDL-4 2005 2002 99.9 Example 1-5 UDL-5 1997 1995 99.9 Example 1-6 UDL-6 1992 1990 99.9 Example 1-7 UDL-7 1991 1990 99.9 Example 1-8 UDL-8 1991 1990 99.9 Example 1-9 UDL-9 1991 1989 99.9 Example 1-10 UDL-10 2004 2001 99.9 Example 1-11 UDL-11 1997 1996 99.9 Example 1-12 UDL-12 2004 2001 99.9 Example 1-13 UDL-13 1992 1990 99.9 Example 1-14 UDL-14 2004 2003 100.0 Example 1-15 UDL-15 1997 1994 99.8 Example 1-16 UDL-16 1995 1994 99.9 Example 1-17 UDL-17 1998 1994 99.8 Comparative Comparative 1990 1978 99.4 Example 1-1 UDL-1 Comparative Comparative 1998 1996 99.9 Example 1-2 UDL-2

As shown in Table 5, the organic films (Examples 1-1 to 1-17) obtained by using the inventive polymers had a film remaining ratio of 99.5% or more after the PGMEA treatment. This indicates that the crosslinking reaction took place by heating and sufficient solvent resistance was exhibited. In contrast, since a monomer compound used in Comparative Example 1-1 had crosslinkable moieties present only at the two terminals. Hence, the film thickness reduction in the solvent resistance test was slightly greater than those in the other examples.

Example 2: Heat Resistance Evaluation (Examples 2-1 to 2-17, Comparative Examples 2-1 to 2-2)

The materials (UDL-1 to -17, Comparative UDL-1 to -2) for forming an organic film were respectively applied onto silicon substrates, and baked in the atmosphere at 350° C. for 60 seconds. Thus, 200-nm coating films were formed, and each film thickness A was measured. The substrate was further baked at 450° C. for another 10 minutes under a nitrogen stream with the oxygen concentration being controlled to 0.2% or less. The resulting film thickness B was measured. Table 6 shows these results.

TABLE 6 Material Film thickness Film thickness Film for forming at 350° C.: at 450° C.: remaining organic film A (Å) B (Å) ratio: % (B/A) Example 2-1 UDL-1 1996 1912 95.8 Example 2-2 UDL-2 2004 1908 95.2 Example 2-3 UDL-3 1991 1976 99.2 Example 2-4 UDL-4 1991 1987 99.8 Example 2-5 UDL-5 1995 1988 99.6 Example 2-6 UDL-6 1995 1988 99.6 Example 2-7 UDL-7 1997 1993 99.8 Example 2-8 UDL-8 2002 1987 99.3 Example 2-9 UDL-9 1997 1982 99.2 Example 2-10 UDL-10 2004 1988 99.2 Example 2-11 UDL-11 1992 1982 99.5 Example 2-12 UDL-12 1993 1980 99.3 Example 2-13 UDL-13 2004 1994 99.5 Example 2-14 UDL-14 1993 1985 99.6 Example 2-15 UDL-15 1992 1986 99.7 Example 2-16 UDL-16 2005 1993 99.4 Example 2-17 UDL-17 2005 1999 99.7 Comparative Comparative 1993 1776 89.1 Example 2-1 UDL-1 Comparative Comparative 1994 1567 78.6 Example 2-2 UDL-2

As shown in Table 6, the film thicknesses of the inventive materials (Examples 2-1 to 2-17) for forming an organic film were reduced by less than 5% even after the baking at 450° C. It is understood that the film thicknesses before the high-temperature baking were maintained even after the 450° C. baking by the inventive materials for forming an organic film. Particularly, as can be seen from Examples 2-3 to 2-17, introducing not an alkyl chain but an aromatic ring as a linking group kept the film remaining ratio at 99% or more. This indicates that the heat resistance is improved. Meanwhile, Comparative Example 2-1 resulted in poor heat resistance due to insufficient crosslinking density as expected from the result of Example 1. In Comparative Example 2-2, the film had sufficient curability as in the result of Example 1, but the heat resistance was low presumably due to the thermal decomposition at the methylene portion constituting the polymer.

Example 3: Hardness Measurement (Examples 3-1 to 3-17, Comparative Examples 3-1 to 3-2)

UDL-1 to -17 and Comparative UDL-1 to -2 prepared above were respectively applied onto silicon substrates, and baked in the atmosphere at 350° C. for 60 seconds. Thus, coating films each having a film thickness of 200 nm were formed. These films were subjected to a nano-indentation test with a SA2 nanoindenter instrument manufactured by TOYO Corporation, and the hardness of each coating film was measured. Table 7 shows the result.

TABLE 7 Material for forming Hardness organic film (GPa) Example 3-1 UDL-1 0.61 Example 3-2 UDL-2 0.60 Example 3-3 UDL-3 0.66 Example 3-4 UDL-4 0.68 Example 3-5 UDL-5 0.65 Example 3-6 UDL-6 0.66 Example 3-7 UDL-7 0.72 Example 3-8 UDL-8 0.70 Example 3-9 UDL-9 0.74 Example 3-10 UDL-10 0.74 Example 3-11 UDL-11 0.65 Example 3-12 UDL-12 0.65 Example 3-13 UDL-13 0.66 Example 3-14 UDL-14 0.66 Example 3-15 UDL-15 0.71 Example 3-16 UDL-16 0.74 Example 3-17 UDL-17 0.66 Comparative Comparative 0.54 Example 3-1 UDL-1 Comparative Comparative 0.63 Example 3-2 UDL-2

As shown in Table 7, films having a hardness of 0.6 or more were formed in Examples 3-1 to 3-17. This verified that finer and stronger films than that in Comparative Example 3-1 were surely formed. This result is suggested from the result in Example 1. Meanwhile, in Comparative Example 3-2, since the curability is sufficient as in the result of Example 1, the film had a hardness of 0.6 or more.

Example 4: Etching Test (Examples 4-1 to 4-17, Comparative Examples 4-1 to 4-2)

[Etching Test with CF₄/CHF₃-Based Gas]

UDL-1 to -17 and Comparative UDL-1 to -2 prepared above were respectively applied onto silicon substrates, and baked in the atmosphere at 350° C. for 60 seconds to form organic films each having a film thickness of 200 nm. Then, an etching test was conducted with CF₄/CHF₃-based gases under the following conditions. In this case, a dry etching apparatus TE-8500 manufactured by Tokyo Electron Limited was used. The film thickness difference of each polymer film between before and after the etching was found to calculate an etching rate (nm/min.). Table 8 shows the result.

The etching conditions were as follows.

Chamber pressure 40.0 Pa RF power 1,000 W CHF₃ gas flow rate 10 ml/min CF₄ gas flow rate 100 ml/min He gas flow rate 200 ml/min Time 20 sec [Etching Test with O₂-Based Gas]

As in the above case, UDL-1 to -17 and Comparative UDL-1 to -2 were respectively applied onto silicon substrates, and baked in the atmosphere at 350° C. for 60 seconds to form organic films each having a film thickness of 200 nm. Then, an etching test was conducted with 02-based gas under the following conditions. In this case, a dry etching apparatus TE-8500 manufactured by Tokyo Electron Limited was used, and the film thickness difference of each polymer film between before and after the etching was found to calculate an etching rate (nm/min.). Table 8 shows the result together with the result of the CF₄/CHF₃-based gas.

The etching conditions were as follows.

Chamber pressure 40.0 Pa RF power 100 W O₂ gas flow rate 30 ml/min N₂ gas flow rate 70 ml/min Time 60 sec

In the etching tests with CF₄/CHF₃-based gas and O₂-based gas, the lower the etching rate, the more excellent the etching resistance of the film.

TABLE 8 CF₄/CHF₃- Material based gas O₂-based gas for forming Etching rate Etching rate organic film (nm/min.) (nm/min.) Example 4-1 UDL-1 98 218 Example 4-2 UDL-2 99 221 Example 4-3 UDL-3 87 213 Example 4-4 UDL-4 88 214 Example 4-5 UDL-5 86 209 Example 4-6 UDL-6 85 210 Example 4-7 UDL-7 86 211 Example 4-8 UDL-8 89 214 Example 4-9 UDL-9 84 208 Example 4-10 UDL-10 84 206 Example 4-11 UDL-11 86 210 Example 4-12 UDL-12 87 213 Example 4-13 UDL-13 86 209 Example 4-14 UDL-14 85 210 Example 4-15 UDL-15 86 211 Example 4-16 UDL-16 85 210 Example 4-17 UDL-17 86 209 Comparative Comparative 101 228 Example 4-1 UDL-1 Comparative Comparative 121 239 Example 4-2 UDL-2

As shown in Table 8, the comparison between Examples 4-1 to 4-17 and Comparative Examples 4-1 to 4-2 shows that in both the etching tests with CF₄/CHF₃-based gas and O₂-based gas, the etching rates in Examples were lower than those in Comparative Examples. This indicates that films excellent in etching resistance were formed in Examples.

Example 5: Pattern Etching Test (Examples 5-1 to 5-17, Comparative Examples 5-1 to 5-2)

UDL-1 to -17 and Comparative UDL-1 to -2 prepared above were respectively applied onto Si wafer substrates. Each of the Si wafer substrates had a diameter of 300 mm, and a SiO₂ film having a film thickness of 200 nm had been formed thereon. Then, the resultant was baked in the atmosphere at 350° C. for 60 seconds to thus form an organic film having a film thickness of 200 nm. A silicon-containing resist underlayer film material (SOG-1) was applied thereon and baked at 220° C. for 60 seconds to form a silicon-containing resist underlayer film having a film thickness of 35 nm. A resist upper layer film material (SL resist for ArF) was applied thereon and baked at 105° C. for 60 seconds to form a resist upper layer film having a film thickness of 100 nm. A liquid immersion top coat material (TC-1) was applied on the resist upper layer film and baked at 90° C. for 60 seconds to form a top coat having a film thickness of 50 nm.

The resist upper layer film material (SL resist for ArF) was prepared by: dissolving a polymer (RP1), an acid generator (PAG1), and a basic compound (Amine1) in a solvent containing 0.1 mass % FC-430 (manufactured by Sumitomo 3M Ltd.) according to proportions in Table 9; and filtering the solution through a 0.1-μm filter made of a fluorinated resin.

TABLE 9 Polymer Acid generator Basic compound Solvent (parts by mass) (parts by mass) (parts by mass) (parts by mass) SL resist RP1 PAG1 Amine1 PGMEA for ArF (100) (6.6) (0.8) (2500)

The structural formulae of the polymer (RP1), acid generator (PAG1), and basic compound (Amine1) thus used are shown below.

The liquid immersion top coat material (TC-1) was prepared by dissolving: a top coat polymer (PP1) in organic solvents according to proportions in Table 10; and filtering the solution through a 0.1-μm filter made of a fluorinated resin.

TABLE 10 Polymer Organic solvent (parts by mass) (parts by mass) TC-1 PP1 diisoamyl ether (2700) (100) 2-methyl-1-butanol (270)

The structural formula of the polymer (PP1) thus used is shown below.

The silicon-containing resist underlayer film material (SOG-1) was prepared by: dissolving a polymer represented by an ArF silicon-containing middle layer film polymer (SiP1) and a crosslinking catalyst (CAT1) in an organic solvent containing 0.1 mass % FC-4430 (manufactured by Sumitomo 3M Ltd.) according to proportions shown in Table 11; and filtering the solution through a filter having a pore size of 0.1 μm and made of a fluorinated resin.

TABLE 11 Thermal crosslinking Polymer catalyst Organic solvent (parts by mass) (parts by mass) (parts by mass) SOG-1 SiP1 CAT1 propylene glycol monoethyl ether (100) (1) (4000)

The structural formulae of the ArF silicon-containing middle layer film polymer (SiP1) and crosslinking catalyst (CAT1) thus used are shown below.

Next, the resulting substrate was exposed to light at various exposure levels with an ArF liquid immersion exposure apparatus (NSR-S610C manufactured by Nikon Corporation, NA: 1.30, σ: 0.98/0.65, 35° s-polarized dipole illumination, 6% halftone phase shift mask), baked (PEB) at 100° C. for 60 seconds, and developed with a 2.38 mass % tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds. Thus, a positive line and space pattern was obtained with the pitch of 100 nm and the resist line width ranging from 50 nm to 30 nm.

Next, dry-etching processing with an etching apparatus Telius manufactured by Tokyo Electron Limited was performed successively as follows. The silicon-containing resist underlayer film was processed using the resist pattern as a mask; the organic film was processed using the silicon-containing resist underlayer film as a mask; and the SiO₂ film was processed using the organic film as a mask.

The etching conditions were as follows.

Conditions for transferring the resist pattern to the SOG film:

Chamber pressure 10.0 Pa RF power 1,500 W CF₄ gas flow rate 15 sccm O₂ gas flow rate 75 sccm Time 15 sec

Conditions for transferring the SOG film pattern to the organic film:

Chamber pressure 2.0 Pa RF power 500 W Ar gas flow rate 75 sccm O₂ gas flow rate 45 sccm Time 120 sec

Conditions for transferring the organic film pattern to the SiO₂ film:

Chamber pressure 2.0 Pa RF power 2,200 W C₅F₁₂ gas flow rate 20 sccm C₂F₆ gas flow rate 10 sccm Ar gas flow rate 300 sccm O₂ gas flow rate 60 sccm Time 90 sec

The pattern cross sections were observed with an electron microscope (S-4700) manufactured by Hitachi, Ltd. The profiles were compared and summarized in Table 12.

TABLE 12 Minimum dimension Profile (nm) without after Profile pattern etching for after Profile twisting Pattern transferring etching for after after Material for profile to resist transferring etching for etching for forming after underlayer to organic transferring transferring organic film development film film to substrate to substrate Example UDL-1 vertical vertical vertical vertical 35 5-1 profile profile profile profile Example UDL-2 vertical vertical vertical vertical 35 5-2 profile profile profile profile Example UDL-3 vertical vertical vertical vertical 33 5-3 profile profile profile profile Example UDL-4 vertical vertical vertical vertical 32 5-4 profile profile profile profile Example UDL-5 vertical vertical vertical vertical 33 5-5 profile profile profile profile Example UDL-6 vertical vertical vertical vertical 33 5-6 profile profile profile profile Example UDL-7 vertical vertical vertical vertical 30 5-7 profile profile profile profile Example UDL-8 vertical vertical vertical vertical 31 5-8 profile profile profile profile Example UDL-9 vertical vertical vertical vertical 29 5-9 profile profile profile profile Example  UDL-10 vertical vertical vertical vertical 29 5-10 profile profile profile profile Example  UDL-11 vertical vertical vertical vertical 33 5-11 profile profile profile profile Example  UDL-12 vertical vertical vertical vertical 33 5-12 profile profile profile profile Example  UDL-13 vertical vertical vertical vertical 33 5-13 profile profile profile profile Example  UDL-14 vertical vertical vertical vertical 33 5-14 profile profile profile profile Example  UDL-15 vertical vertical vertical vertical 30 5-15 profile profile profile profile Example  UDL-16 vertical vertical vertical vertical 29 5-16 profile profile profile profile Example  UDL-17 vertical vertical vertical vertical 33 5-17 profile profile profile profile Comparative Comparative vertical vertical vertical vertical 40 Example 5-1 UDL-1 profile profile profile profile Comparative Comparative vertical vertical vertical vertical 34 Example 5-2 UDL-2 profile profile profile profile

As shown from the results of the inventive materials for forming an organic film (Examples 5-1 to 5-17) in Table 12, the resist upper layer film patterns were favorably transferred to the final substrates in all the cases. This confirmed that the inventive materials for forming an organic film are suitably used as materials for organic film in multilayer resist method. Meanwhile, in accordance with the resist line widths formed by the light exposure, the pattern dimension transferred to the substrate was also changed. In Comparative Example 5-1, the patterns were twisted at the line width of approximately 40 nm. In contrast, in Examples 5-1 to 5-17 using the inventive polymers, no twisting occurred even when the pattern dimension was 35 nm or less. This revealed that the twisting resistance was high. It is understood that as in the case of the inventive polymers, when a fine and high-strength film having a hardness exceeding 0.60 GPa is formed, high twisting resistance is obtained by using such an organic film.

Example 6: Planarizing Property Evaluation (Examples 6-1 to 6-12, Comparative Example 6-1)

The materials (UDL-3, -5, -6, -7, -9, -11 to -17, Comparative UDL-2) for forming an organic film were respectively applied onto SiO₂ substrates (8 in FIG. 2) each having a giant isolated trench pattern (trench width: 10 μm, trench depth: 0.10 μm), and baked in the atmosphere at 350° C. for 60 seconds. Then, a step (delta in FIG. 2) between the trench portion and the non-trench portion of the resulting organic film (7 in FIG. 2) was observed with an atomic force microscope (AFM) NX10 manufactured by Park systems Corp. Table 13 shows the result. In this evaluation, the smaller the step, the better the planarizing property. Note that, in this evaluation, a trench pattern having a depth of 0.10 μm was planarized using a material for forming an organic film to have a film thickness of approximately 0.2 μm. This is a strict evaluation condition to evaluate the planarizing property.

TABLE 13 Material for forming Step organic film (nm) Example 6-1 UDL-3 80 Example 6-2 UDL-5 65 Example 6-3 UDL-6 85 Example 6-4 UDL-7 70 Example 6-5 UDL-9 80 Example 6-6 UDL-11 85 Example 6-7 UDL-12 70 Example 6-8 UDL-13 55 Example 6-9 UDL-14 75 Example 6-10 UDL-15 60 Example 6-11 UDL-16 70 Example 6-12 UDL-17 65 Comparative Comparative 90 Example 6-1 UDL-2

As shown in Table 13, the organic films obtained from the inventive materials for forming an organic film had smaller steps between the trench and non-trench portions than that in Comparative Example 6-1. This verified that the inventive materials are excellent in planarizing property. This is because the inventive polymers are excellent in heat resistance as demonstrated in Example 2, so that the film shrinkage by baking is suppressed. Moreover, the comparison between Examples 6-7 to 6-12 with the high-boiling-point solvent added and Examples 6-1 to 6-6 without the high-boiling-point solvent shows that adding the high-boiling-point solvent improves the planarizing property.

From the above, the inventive material for forming an organic film enables heat resistance, high etching resistance, and excellent twisting resistance during etching. The inventive material is quite useful for an organic film used in multilayer resist processes, particularly three-layer resist process, for ultrafine and highly precise patterning. 

1. A material for forming an organic film, comprising: (A) a polymer comprising a repeating unit shown by the following general formula (1); and (B) an organic solvent,

wherein AR1, AR2, AR3, and AR4 each represent a benzene ring or a naphthalene ring; W1 represents a tetravalent organic group having 6 to 70 carbon atoms and at least one or more aromatic rings; and W2 represents a divalent organic group having 1 to 50 carbon atoms.
 2. The material for forming an organic film according to claim 1, wherein the polymer is a polymer comprising a repeating unit shown by the following general formula (2) or (3),

wherein W2, AR1, AR2, AR3, and AR4 are as defined above; and AR5 represents a benzene ring or a naphthalene ring, and

wherein W2, AR1, AR2, AR3, and AR4 are as defined above; W3 represents a single bond or a divalent organic group having 1 to 58 carbon atoms; and AR6 and AR7 each represent a benzene ring or a naphthalene ring.
 3. The material for forming an organic film according to claim 1, wherein the polymer is a polymer comprising a repeating unit shown by the following general formula (4) or (5),

wherein AR5 represents a benzene ring or a naphthalene ring, and

wherein W3 represents a single bond or a divalent organic group having 1 to 58 carbon atoms; and AR6 and AR7 each represent a benzene ring or a naphthalene ring.
 4. The material for forming an organic film according to claim 1, wherein the polymer comprises a terminal structure shown by any of the following general formula (6) or (7),

wherein AR8 and AR9 each represent a benzene ring or a naphthalene ring; R1 represents a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms; and * represents an attachment point to the polymer, and

wherein AR10 and AR11 each represent a benzene ring or a naphthalene ring; R2 represents any in the following formula (8); “n” represents an integer of 1 to 4; W4 represents an organic group with a valency of n+2 having 6 to 70 carbon atoms and at least one or more aromatic rings; and * represents an attachment point to the polymer,

wherein a broken line represents a bonding arm.
 5. The material for forming an organic film according to claim 1, wherein the polymer has a weight-average molecular weight of 500 to
 5000. 6. The material for forming an organic film according to claim 1, wherein the organic solvent (B) is a mixture of one or more organic solvents each having a boiling point of lower than 180° C. and one or more organic solvents each having a boiling point of 180° C. or higher.
 7. The material for forming an organic film according to claim 1, wherein the material for forming an organic film further comprises one or more of (C) an acid generator, (D) a surfactant, (E) a crosslinking agent, and (F) a plasticizer.
 8. A patterning process for forming a pattern in a substrate to be processed, comprising: forming an organic film by using the material for forming an organic film according to claim 1 on a substrate to be processed; forming a silicon-containing resist underlayer film by using a silicon-containing resist underlayer film material on the organic film; forming a resist upper layer film by using a photoresist composition on the silicon-containing resist underlayer film; forming a circuit pattern in the resist upper layer film; transferring the pattern to the silicon-containing resist underlayer film by etching while using the resist upper layer film having the formed pattern as a mask; transferring the pattern to the organic film by etching while using the silicon-containing resist underlayer film having the transferred pattern as a mask; and further forming the pattern in the substrate to be processed by etching while using the organic film having the transferred pattern as a mask.
 9. A patterning process for forming a pattern in a substrate to be processed, comprising: forming an organic film by using the material for forming an organic film according to claim 1 on a substrate to be processed; forming a silicon-containing resist underlayer film by using a silicon-containing resist underlayer film material on the organic film; forming an organic antireflective coating film (BARC) on the silicon-containing resist underlayer film; forming a resist upper layer film by using a photoresist composition on the BARC, so that a 4-layered film structure is constructed; forming a circuit pattern in the resist upper layer film; transferring the pattern to the BARC film and the silicon-containing resist underlayer film by etching while using the resist upper layer film having the formed pattern as a mask; transferring the pattern to the organic film by etching while using the silicon-containing resist underlayer film having the transferred pattern as a mask; and further forming the pattern in the substrate to be processed by etching the substrate to be processed while using the organic film having the transferred pattern as a mask.
 10. A patterning process for forming a pattern in a substrate to be processed, comprising: forming an organic film by using the material for forming an organic film according to claim 1 on a substrate to be processed; forming an inorganic hard mask selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the organic film; forming a resist upper layer film by using a photoresist composition on the inorganic hard mask; forming a circuit pattern in the resist upper layer film; transferring the pattern to the inorganic hard mask by etching while using the resist upper layer film having the formed pattern as a mask; transferring the pattern to the organic film by etching while using the inorganic hard mask having the transferred pattern as a mask; and further forming the pattern in the substrate to be processed by etching the substrate to be processed while using the organic film having the transferred pattern as a mask.
 11. A patterning process for forming a pattern in a substrate to be processed, comprising: forming an organic film by using the material for forming an organic film according to claim 1 on a substrate to be processed; forming an inorganic hard mask selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the organic film; forming an organic antireflective coating film (BARC) on the inorganic hard mask; forming a resist upper layer film by using a photoresist composition on the BARC, so that a 4-layered film structure is constructed; forming a circuit pattern in the resist upper layer film; transferring the pattern to the BARC film and the inorganic hard mask by etching while using the resist upper layer film having the formed pattern as a mask; transferring the pattern to the organic film by etching while using the inorganic hard mask having the transferred pattern as a mask; and further forming the pattern in the substrate to be processed by etching the substrate to be processed while using the organic film having the transferred pattern as a mask.
 12. The patterning process according to claim 10, wherein the inorganic hard mask is formed by a CVD method or an ALD method.
 13. The patterning process according to claim 8, wherein the pattern is formed in the resist upper layer film by a method of a photolithography with a wavelength of 10 nm or more and 300 nm or less, a direct drawing with electron beam, nanoimprinting, or a combination thereof.
 14. The patterning process according to claim 8, wherein alkaline development or organic solvent development is employed as a development method in the patterning process.
 15. The patterning process according to claim 8, wherein the substrate to be processed is a semiconductor device substrate, a metal film, a metal carbide film, a metal oxide film, a metal nitride film, a metal oxycarbide film, or a metal oxynitride film.
 16. The patterning process according to claim 15, wherein the metal is silicon, titanium, tungsten, hafnium, zirconium, chromium, germanium, cobalt, copper, silver, gold, aluminum, indium, gallium, arsenic, palladium, iron, tantalum, iridium, manganese, molybdenum, ruthenium, or an alloy thereof.
 17. A polymer comprising a repeating unit shown by the following general formula (1),

wherein AR1, AR2, AR3, and AR4 each represent a benzene ring or a naphthalene ring; W1 represents a tetravalent organic group having 6 to 70 carbon atoms and at least one or more aromatic rings; and W2 represents a divalent organic group having 1 to 50 carbon atoms.
 18. The polymer according to claim 17, wherein the polymer comprises a repeating unit shown by the following general formula (2) or (3),

wherein W2, AR1, AR2, AR3, and AR4 are as defined above; and AR5 represents a benzene ring or a naphthalene ring, and

wherein W2, AR1, AR2, AR3, and AR4 are as defined above; W3 represents a single bond or a divalent organic group having 1 to 58 carbon atoms; and AR6 and AR7 each represent a benzene ring or a naphthalene ring.
 19. The polymer according to claim 17, wherein the polymer comprises a repeating unit shown by the following general formula (4) or (5),

wherein AR5 represents a benzene ring or a naphthalene ring, and

wherein W3 represents a single bond or a divalent organic group having 1 to 58 carbon atoms; and AR6 and AR7 each represent a benzene ring or a naphthalene ring.
 20. The polymer according to claim 17, wherein the polymer comprises a terminal structure shown by any of the following general formula (6) or (7),

wherein AR8 and AR9 each represent a benzene ring or a naphthalene ring; R1 represents a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms; and * represents an attachment point to the polymer, and

wherein AR10 and AR11 each represent a benzene ring or a naphthalene ring; R2 represents any in the following formula (8); “n” represents an integer of 1 to 4; W4 represents an organic group with a valency of n+2 having 6 to 70 carbon atoms and at least one or more aromatic rings; and * represents an attachment point to the polymer,

wherein a broken line represents a bonding arm. 